Mention badge colors on startpage

static/index.html

@@ -51,6 +51,42 @@ would render this badge:
 </pre>
 </div>
 
+<h2>Colors</h2>
+
+<div>
+<p>
+You can generate badges with custom colors via the <code>color</code> query parameter. The following predefined colors
+are supported:
+</p>
+
+<pre>
+
+<img src="/badge?color=brightgreen" />
+<img src="/badge?color=green" />
+<img src="/badge?color=yellowgreen" />
+<img src="/badge?color=yellow" />
+<img src="/badge?color=orange" />
+<img src="/badge?color=red" />
+<img src="/badge?color=blue" />
+<img src="/badge?color=lightgrey" />
+
+<img src="/badge?color=success" />
+<img src="/badge?color=important" />
+<img src="/badge?color=critical" />
+<img src="/badge?color=informational" />
+<img src="/badge?color=inactive" />
+
+</pre>
+
+<p>
+You can also pass HTML color codes:
+</p>
+
+<pre>
+<img src="/badge?color=ff69b4" /> <img src="/badge?color=9cf" />
+</pre>
+</div>
+
 <h2>Source Code</h2>
 
 <div>