Add some basic typography, tweak the Markdown

This commit adds some basic type sizes, weights and spacing for HTML
elements scoped inside a `.documentation` container.

It also tweaks some of the Markdown so that it renders the same as it
does on Github.

app/assets/stylesheets/main.scss

@@ -52,6 +52,7 @@ $path: '/static/images/';
 
 @import 'views/job';
 @import 'views/edit-template';
+@import 'views/documenation';
 
 // TODO: break this up
 @import 'app';