update mainpage doc listing for rc1

Author: tacaswell

versions.html

@@ -2,7 +2,7 @@
 
 <ul>
   <li><a href="/devdocs/index.html">2.x</a> Latest git master (unstable)</a></li>
-  <li><a href="/2.0.0b4/index.html">2.0.0b4</a> 2.0 beta release.</a></li>
+  <li><a href="/2.0.0rc1/index.html">2.0.0rc1</a> 2.0 Release Candidate.</a></li>
   <li><a href="/1.5.3/index.html">1.5.3</a> Latest stable version.</a></li>
   <li><a href="/1.4.3/index.html">1.4.3</a> Previous stable version.</a></li>
   <li><a href="/1.3.1/index.html">1.3.1</a> Older stable version.</a></li>