Merge branch 'markdown-parser-documentation' into 'master'

Adds mention of Redcarpet as Markdown parser in docs

It makes it easier for users to find the source of issues related to
Markdown parsing.

[ci skip]

See merge request !3168

doc/markdown/markdown.md

@@ -29,6 +29,8 @@
 
 ## GitLab Flavored Markdown (GFM)
 
+_GitLab uses the [Redcarpet Ruby library][redcarpet] for Markdown processing._
+
 For GitLab we developed something we call "GitLab Flavored Markdown" (GFM). It extends the standard Markdown in a few significant ways to add some useful functionality.
 
 You can use GFM in
@@ -88,8 +90,8 @@ GFM will autolink almost any URL you copy and paste into your text.
 
 ## Code and Syntax Highlighting
 
-_GitLab uses the [rouge ruby library][rouge] for syntax highlighting. For a
-list of supported languages visit the rouge website._
+_GitLab uses the [Rouge Ruby library][rouge] for syntax highlighting. For a
+list of supported languages visit the Rouge website._
 
 Blocks of code are either fenced by lines with three back-ticks <code>```</code>, or are indented with four spaces. Only the fenced code blocks support syntax highlighting.
 
@@ -591,3 +593,4 @@ By including colons in the header row, you can align the text within that column
 - [Dillinger.io](http://dillinger.io) is a handy tool for testing standard markdown.
 
 [rouge]: http://rouge.jneen.net/ "Rouge website"
+[redcarpet]: https://github.com/vmg/redcarpet "Redcarpet website"