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/views/documenation.scss

@@ -0,0 +1,64 @@
+.documentation {
+
+  h1,
+  h2,
+  h3,
+  h4,
+  h5,
+  h6 {
+    margin: $gutter 0 $gutter-half 0;
+  }
+  
+  h1 {
+    @include heading-48;    
+    font-weight: bold;
+  }
+
+  h2 {
+    @include heading-36;    
+    font-weight: bold;
+  }
+
+  h3 {
+    @include heading-24;    
+    font-weight: bold;
+  }
+
+  h4,
+  h5,
+  h6 {
+    @include bold-19;    
+  }
+
+  p,
+  ul {
+    margin: 0 0 20px 0;
+  }
+
+  ul {
+    list-style: disc;
+    margin: 0 0 20px 20px;
+  }
+
+  ol {
+    list-style: decimal;
+    margin: 0 0 20px 20px;
+  }
+
+  blockquote {
+    border-left: 8px solid $border-colour;
+    padding: 0 0 0 20px;
+    margin: 0 0 20px 0;
+  }
+
+  .highlight {
+    margin: 0 0 20px 0;
+    background: #F8F8F8;
+  }
+
+  strong,
+  em {
+    font-weight: bold;
+  }
+
+}