Cover "Edit in Prose" functionality.

_posts/help/2012-06-20-handbook.md

@@ -49,8 +49,34 @@ Metadata defaults can be used to prepopulate metadata of posts based on the dire
           img:  "Project Thumbnail"
 
 
+# Make your website editable
 
-# Known Issue
+You have probably seen the **"Edit in Prose"**-link that sits below our help articles, like this one (scroll down). You should consider doing that with your website too in order allow readers to [contribute](http://prose.io/help/eventually-consistent.html).
+
+Essentially, this is as easy as including a link to the Prose edit page of the corresponding markdown file. You can copy it over from GitHub and add `prose.io/#` instead of `github.com/` as a prefix.
+
+For the Prose help pages we just added a `prose_link` property to the YAML frontmatter of our source files.
+
+```
+---
+prose_link: http://prose.io/#prose/prose/edit/gh-pages/_posts/help/2012-06-20-internals.md
+---
+```
+
+And in the help pages template used this markup:
+
+```html
+<div class="improve-article-wrapper">
+  <div class="improve-article">
+    <a class="button" href="{{ page.prose_link }}">Edit in Prose</a>
+    <p>
+      This article has been written and published using <a href="http://prose.io" target="_blank">Prose</a>. Please help improving this documentation by contributing to the text.
+    </p>
+  </div>
+</div>
+```
+
+# Known Issues
 
 This is brand-new software, and there are some known issues you should be aware of.