Add docs about custom markdown processor

site/_posts/2014-05-05-jekyll-2-0-0-released.markdown

@@ -14,7 +14,7 @@ Jam-packed with some [highly-requested features and bugfixes galore][changelog],
 2. [Brand new site template](https://github.com/jekyll/jekyll/pull/2050#issuecomment-35938016) (thanks [@jglovier][]!) - Getting started with Jekyll just got a lot easier and a lot more beautiful. Just run `jekyll new <path>` and you're good to go.
 3. [Native Sass & CoffeeScript support](/docs/assets/) - We love CSS and JavaScript as much as the next guy, but there will always be a special place in our hearts for Sass and CoffeeScript. We now offer native support for these file types &mdash; no more messing around with Rake or Grunt!
 4. [YAML Front-Matter defaults](/docs/configuration/#frontmatter_defaults) - If you've set `layout: post` more than once in your life, you'll love this new feature: set front-matter defaults for a given directory or type.
-5. [Custom markdown processors](/docs/configuration/#custom_markdown_processors) - Always wanted to use your favourite home-grown Markdown converter, but couldn't with Jekyll? Now you can. Simply specify `markdown: MyConverterClass` and you're on your way.
+5. [Custom markdown processors](/docs/configuration/#custom-markdown-processors) - Always wanted to use your favourite home-grown Markdown converter, but couldn't with Jekyll? Now you can. Simply specify `markdown: MyConverterClass` and you're on your way.
 6. [Addition of `where` and `group_by` Liquid filters](/docs/templates/#filters) - Simplifying your Liquid templates one filter at a time. The `where` filter selects from an array all items within which have a given value for a property. The `group_by` filter groups all items in an array which have the same value for a given property.
 7. [Switch from Maruku to Kramdown as default markdown converter](https://github.com/jekyll/jekyll/pull/1988) - Maruku is dead. We've replaced it with the converter which has the closest feature parity: Kramdown!
 

site/docs/configuration.md

@@ -454,3 +454,30 @@ For example, in your `_config.yml`:
 
     kramdown:
       input: GFM
+
+### Custom Markdown Processors
+
+If you're interested in creating a custom markdown processor, you're in luck! Create a new class in the `Jekyll::Converters::Markdown` namespace:
+
+{% highlight ruby %}
+class Jekyll::Converters::Markdown::MyCustomProcessor
+  def initialize(config)
+    require 'funky_markdown'
+    @config = config
+  rescue LoadError
+    STDERR.puts 'You are missing a library required for Markdown. Please run:'
+    STDERR.puts '  $ [sudo] gem install funky_markdown'
+    raise FatalException.new("Missing dependency: funky_markdown")
+  end
+
+  def convert(content)
+    ::FunkyMarkdown.new(content).convert
+  end
+end
+{% endhighlight %}
+
+Once you've created your class and have it properly setup either as a plugin in the `_plugins` folder or as a gem, specify it in your `_config.yml`:
+
+{% highlight yaml %}
+markdown: MyCustomProcessor
+{% endhighlight %}