Add improved docs

Author: wooorm

readme.md

@@ -8,46 +8,106 @@
 [![Backers][backers-badge]][collective]
 [![Chat][chat-badge]][chat]
 
-Extension for [`mdast-util-from-markdown`][from-markdown] and/or
-[`mdast-util-to-markdown`][to-markdown] to support the [generic directives
-proposal][prop] (`:cite[smith04]`, `::youtube[Video of a cat in a
-box]{v=01ab2cd3efg}`, and such) in **[mdast][]**.
-When parsing (`from-markdown`), must be combined with
-[`micromark-extension-directive`][extension].
-
-See [`micromark-extension-directive`][extension] for how the syntax works.
-This utility handles parsing and serializing.
-[Traverse the tree][traversal] to change them to whatever you please.
+[mdast][] extensions to parse and serialize [generic directives proposal][prop]
+(`:cite[smith04]`, `::youtube[Video of a cat in a box]{v=01ab2cd3efg}`, and
+such).
+
+## Contents
+
+*   [What is this?](#what-is-this)
+*   [When to use this](#when-to-use-this)
+*   [Install](#install)
+*   [Use](#use)
+*   [API](#api)
+    *   [`directiveFromMarkdown`](#directivefrommarkdown)
+    *   [`directiveToMarkdown`](#directivetomarkdown)
+*   [Syntax tree](#syntax-tree)
+    *   [Nodes](#nodes)
+    *   [Mixin](#mixin)
+    *   [`Directive`](#directive)
+*   [Types](#types)
+*   [Compatibility](#compatibility)
+*   [Related](#related)
+*   [Contribute](#contribute)
+*   [License](#license)
+
+## What is this?
+
+This package contains extensions that add support for generic directives to
+[`mdast-util-from-markdown`][mdast-util-from-markdown] and
+[`mdast-util-to-markdown`][mdast-util-to-markdown].
+
+This package handles the syntax tree.
+You can use this with some more code to match your specific needs, to allow for
+anything from callouts, citations, styled blocks, forms, embeds, spoilers, etc.
+[Traverse the tree][traversal] to change directives to whatever you please.
 
 ## When to use this
 
-Use this if you’re dealing with the AST manually.
-It might be better to use [`remark-directive`][plugin] with **[remark][]**,
-which includes this but provides a nicer interface and makes it easier to
-combine with hundreds of plugins.
+These tools are all rather low-level.
+In most cases, you’d want to use [`remark-directive`][remark-directive] with
+remark instead.
+
+Directives are one of the four ways to extend markdown: an arbitrary extension
+syntax (see [Extending markdown][extending-mmarkdown] in micromark’s docs for
+the alternatives and more info).
+This mechanism works well when you control the content: who authors it, what
+tools handle it, and where it’s displayed.
+When authors can read a guide on how to embed a tweet but are not expected to
+know the ins and outs of HTML or JavaScript.
+Directives don’t work well if you don’t know who authors content, what tools
+handle it, and where it ends up.
+Example use cases are a docs website for a project or product, or blogging tools
+and static site generators.
+
+When working with `mdast-util-from-markdown`, you must combine this package with
+[`micromark-extension-directive`][extension].
+
+This utility does not handle how directives are turned to HTML.
+You must [traverse the tree][traversal] to change directives to whatever you
+please.
 
 ## Install
 
-This package is [ESM only](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c):
-Node 12+ is needed to use it and it must be `import`ed instead of `require`d.
-
-[npm][]:
+This package is [ESM only][esm].
+In Node.js (version 12.20+, 14.14+, or 16.0+), install with [npm][]:
 
 ```sh
 npm install mdast-util-directive
 ```
 
+In Deno with [`esm.sh`][esmsh]:
+
+```js
+import {directiveFromMarkdown, directiveToMarkdown} from 'https://esm.sh/mdast-util-directive@2'
+```
+
+In browsers with [`esm.sh`][esmsh]:
+
+```html
+<script type="module">
+  import {directiveFromMarkdown, directiveToMarkdown} from 'https://esm.sh/mdast-util-directive@2?bundle'
+</script>
+```
+
 ## Use
 
-Say our module, `example.js`, looks as follows:
+Say our document `example.md` contains:
+
+```markdown
+A lovely language know as :abbr[HTML]{title="HyperText Markup Language"}.
+```
+
+…and our module `example.js` looks as follows:
 
 ```js
+import fs from 'node:fs/promises'
 import {fromMarkdown} from 'mdast-util-from-markdown'
 import {toMarkdown} from 'mdast-util-to-markdown'
 import {directive} from 'micromark-extension-directive'
 import {directiveFromMarkdown, directiveToMarkdown} from 'mdast-util-directive'
 
-const doc = 'A lovely language know as :abbr[HTML]{title="HyperText Markup Language"}.'
+const doc = await fs.readFile('example.md')
 
 const tree = fromMarkdown(doc, {
   extensions: [directive()],
@@ -61,7 +121,7 @@ const out = toMarkdown(tree, {extensions: [directiveToMarkdown]})
 console.log(out)
 ```
 
-Now, running `node example` yields (positional info removed for brevity):
+…now running `node example.js` yields (positional info removed for brevity):
 
 ```js
 {
@@ -90,21 +150,21 @@ A lovely language know as :abbr[HTML]{title="HyperText Markup Language"}.
 
 ## API
 
+This package exports the identifiers `directiveFromMarkdown` and
+`directiveToMarkdown`.
+There is no default export.
+
 ### `directiveFromMarkdown`
 
+Extension for [`mdast-util-from-markdown`][mdast-util-from-markdown].
+
 ### `directiveToMarkdown`
 
-Support the [generic directives proposal][prop].
-The exports are extensions, respectively
-for [`mdast-util-from-markdown`][from-markdown] and
-[`mdast-util-to-markdown`][to-markdown].
+Extension for [`mdast-util-to-markdown`][mdast-util-to-markdown].
 
 There are no options, but passing [`options.quote`][quote] to
 `mdast-util-to-markdown` is honored for attributes.
 
-This utility handles parsing and serializing.
-[Traverse the tree][traversal] to change them to whatever you please.
-
 ## Syntax tree
 
 The following interfaces are added to **[mdast][]** by this utility.
@@ -256,25 +316,52 @@ or hast).
 > included.
 > In JavaScript, both `null` and `undefined` must be similarly ignored.
 
+## Types
+
+This package is fully typed with [TypeScript][].
+It exports the additional types `ContainerDirective`, `LeafDirective`,
+`TextDirective`, and `Directive`.
+
+It also registers the node types with `@types/mdast`.
+If you’re working with the syntax tree, make sure to import this utility
+somewhere in your types, as that registers the new node types in the tree.
+
+```js
+/**
+ * @typedef {import('mdast-util-directive')}
+ */
+
+import {visit} from 'unist-util-visit'
+
+/** @type {import('mdast').Root} */
+const tree = getMdastNodeSomeHow()
+
+visit(tree, (node) => {
+  // `node` can now be one of the nodes for directives.
+})
+```
+
+## Compatibility
+
+Projects maintained by the unified collective are compatible with all maintained
+versions of Node.js.
+As of now, that is Node.js 12.20+, 14.14+, and 16.0+.
+Our projects sometimes work with older versions, but this is not guaranteed.
+
+This plugin works with `mdast-util-from-markdown` version 1+ and
+`mdast-util-to-markdown` version 1+.
+
 ## Related
 
-*   [`remarkjs/remark`][remark]
-    — markdown processor powered by plugins
-*   [`remarkjs/remark-directive`][plugin]
+*   [`remarkjs/remark-directive`][remark-directive]
     — remark plugin to support generic directives
-*   [`micromark/micromark`][micromark]
-    — the smallest commonmark-compliant markdown parser that exists
 *   [`micromark/micromark-extension-directive`][extension]
     — micromark extension to parse directives
-*   [`syntax-tree/mdast-util-from-markdown`][from-markdown]
-    — mdast parser using `micromark` to create mdast from markdown
-*   [`syntax-tree/mdast-util-to-markdown`][to-markdown]
-    — mdast serializer to create markdown from mdast
 
 ## Contribute
 
-See [`contributing.md` in `syntax-tree/.github`][contributing] for ways to get
-started.
+See [`contributing.md`][contributing] in [`syntax-tree/.github`][health] for
+ways to get started.
 See [`support.md`][support] for ways to get help.
 
 This project has a [code of conduct][coc].
@@ -315,34 +402,40 @@ abide by its terms.
 
 [npm]: https://docs.npmjs.com/cli/install
 
+[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
+
+[esmsh]: https://esm.sh
+
+[typescript]: https://www.typescriptlang.org
+
 [license]: license
 
 [author]: https://wooorm.com
 
-[contributing]: https://github.com/syntax-tree/.github/blob/HEAD/contributing.md
+[health]: https://github.com/syntax-tree/.github
+
+[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md
 
-[support]: https://github.com/syntax-tree/.github/blob/HEAD/support.md
+[support]: https://github.com/syntax-tree/.github/blob/main/support.md
 
-[coc]: https://github.com/syntax-tree/.github/blob/HEAD/code-of-conduct.md
+[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md
 
 [mdast]: https://github.com/syntax-tree/mdast
 
-[remark]: https://github.com/remarkjs/remark
+[mdast-util-from-markdown]: https://github.com/syntax-tree/mdast-util-from-markdown
 
-[plugin]: https://github.com/remarkjs/remark-directive
+[mdast-util-to-markdown]: https://github.com/syntax-tree/mdast-util-to-markdown
 
-[from-markdown]: https://github.com/syntax-tree/mdast-util-from-markdown
+[quote]: https://github.com/syntax-tree/mdast-util-to-markdown#optionsquote
 
-[to-markdown]: https://github.com/syntax-tree/mdast-util-to-markdown
+[extension]: https://github.com/micromark/micromark-extension-directive
 
-[micromark]: https://github.com/micromark/micromark
+[remark-directive]: https://github.com/remarkjs/remark-directive
 
-[extension]: https://github.com/micromark/micromark-extension-directive
+[extending-mmarkdown]: https://github.com/micromark/micromark#extending-markdown
 
 [prop]: https://talk.commonmark.org/t/generic-directives-plugins-syntax/444
 
-[quote]: https://github.com/syntax-tree/mdast-util-to-markdown#optionsquote
-
 [traversal]: https://unifiedjs.com/learn/recipe/tree-traversal/
 
 [dfn-parent]: https://github.com/syntax-tree/mdast#parent