add class documentation link to page header

plugin-dev.html

@@ -9,7 +9,7 @@ nav: 3
     <div class="inner">
         <h1 class="aligncenter">Create your own plugins &amp; themes</h1>
         <p class="description aligncenter">
-            Pico is highly customizable - the possibilites are endless when you're in control.
+            Below is our developer documentation, you may also refer to Pico's <a href="phpDocumentor/">class documentation</a>
         </p><br />
 
         <div class="one-fourth">