Fix YARD doc markdown rendering

Author: duffn

.gitignore

@@ -35,6 +35,7 @@ dist
 Gemfile.lock
 gemfiles/*.lock
 tmp
+.yardoc
 
 ## Rubinius
 .rbx

.yardopts

@@ -1 +1,2 @@
 --asset grape.png
+--markup markdown

CHANGELOG.md

@@ -8,6 +8,7 @@
 * [#2302](https://github.com/ruby-grape/grape/pull/2302): Rack < 3 and update rack-test - [@ericproulx](https://github.com/ericproulx).
 * [#2303](https://github.com/ruby-grape/grape/pull/2302): Rack >= 1.3.0 - [@ericproulx](https://github.com/ericproulx).
 * [#2301](https://github.com/ruby-grape/grape/pull/2301): Revisit GH workflows - [@ericproulx](https://github.com/ericproulx).
+* [#2310](https://github.com/ruby-grape/grape/pull/2310): Fix YARD docs markdown rendering - [@duffn](https://github.com/duffn).
 * Your contribution here.
 
 #### Fixes

CONTRIBUTING.md

@@ -58,6 +58,8 @@ Make sure that `bundle exec rake` completes without errors.
 
 Document any external behavior in the [README](README.md).
 
+You should also document code as necessary, using current code as examples. This project uses [YARD](https://yardoc.org/). You can run and preview the docs locally by [installing `yard`](https://yardoc.org/), running `yard server --reload` and view the docs at http://localhost:8808.
+
 #### Update Changelog
 
 Add a line to [CHANGELOG](CHANGELOG.md) under *Next Release*. Make it look like every other line, including your name and link to your Github account.