[MNGSITE-529] Rename "Goals" to "Plugin Documentation"

Author: Bukama

src/site/site.xml

@@ -28,7 +28,7 @@ under the License.
 
     <menu name="Overview">
       <item name="Introduction" href="index.html"/>
-      <item name="Goals" href="plugin-info.html"/>
+      <item name="Plugin Documentation" href="plugin-info.html"/>
       <item name="Usage" href="usage.html"/>
       <item name="FAQ" href="faq.html"/>
       <!-- According to https://issues.apache.org/jira/browse/MNGSITE-152 -->