Move WeaveDNS docs to docs.weave.works (close #471)

site/index.md

@@ -10,6 +10,9 @@ layout: default
  * [Troubleshooting](troubleshooting.html)
  * [Building](building.html)
  * [How it works](how-it-works.html)
+ * *WeaveDNS*
+   * [User guide](weavedns-readme.html)
+   * [Design notes](weavedns-design.html)
  * [Contact information](https://github.com/weaveworks/weave#contact-us)
  * *Installation Notes*
    * [Using with boot2docker](boot2docker.html)