doc update: add note about using local docs with development version

index.html

@@ -457,6 +457,12 @@ USE_OSGPLUGIN(<plugin2>)
 
     <pre>git clone -b master https://github.com/mxe/mxe.git</pre>
 
+    <p>
+    <strong>N.B.</strong> when using the development version,
+    ensure you use the local documentation (index.html) -
+    the website reflects the stable branch.
+    </p>
+
     <p>
     To retrieve updates, run:
     </p>