Merge pull request rust-lang#195 from Havvy/community

Add contributing document

Author: QuietMisdreavus

CONTRIBUTING.md

@@ -0,0 +1,60 @@
+Thank you for your interest in contributing to the Rust Reference!
+
+There are a few ways of helping with the reference: critiquing the reference,
+editing the reference, fixing incorrect information, adding examples and
+glossary entries, and documenting new or otherwise undocumented features in
+Rust.
+
+For awhile, the Reference was basically ignored, and Rust continued gaining
+new features or changing old ones. It was also basically the introduction
+document before the first edition of the Rust book, and constantly in flux from
+the huge churn of the language design before v1.0.0. So there's a lot that's
+wrong, too teachy for people who should have basic understanding of Rust, or
+is too shallow for the Reference. As such, we
+have the warning saying there's work that needs to be done. Eventually, we plan
+to make sure everything is well documented enough that we can remove the
+warning.
+
+## Critiquing the Reference
+
+This is the easiest way to contribute. Basically, as you read the reference, if
+you find something confusing, incorrect, or missing, then you can file an issue
+against the reference explaining your concerns.
+
+## Editing the Reference
+
+Typos and incorrect links get through from time to time. Should you find them,
+we welcome PRs to fix them. Additionally, larger editing jobs that help remove
+the number of parentheticals, remove comma splices, italicize term definitions
+and other similar tasks are helpful.
+
+## Adding Examples and Glossary Entries
+
+Examples are great. Many people will only read examples and ignore the prose.
+Ideally, every facet of every feature will have an example.
+
+Likewise, the reference has a glossary. It doesn't need to explain every facet
+of every feature nor contain every definition, but it does need to be expanded
+upon. Ideally entries in the glossary link to the associated documentation.
+
+## Adding Documentation
+
+There are a lot of features that are not documented at all or are documented
+poorly. This is the hardest, but definitely most valuable. Pick something from
+["Document all features"][9] or a [missing feature] tag, and write about it.
+
+While writing, you may find it handy to have a [playpen] open to test out what
+you are documenting.
+
+Feel free to take information from the standard library and Rustonomicon as
+appropriate.
+
+Note that we don't write documentation for purely library features such as
+threads and IO and we don't write about Rust in the future. Documentation is
+written as if the current stable release of Rust is the last release. If you
+want to write about Rust in the future, you want [the Unstable book][unstable].
+
+[9]: https://github.com/rust-lang-nursery/reference/issues/9
+[missing feature]: https://github.com/rust-lang-nursery/reference/issues?q=is%3Aissue+is%3Aopen+label%3A%22Missing+Feature%22
+[playpen]: https://play.rust-lang.org/
+[unstable]: https://doc.rust-lang.org/nightly/unstable-book/