docs: document how to apply a candidate to a stable branch

Reviewed-by: Brian Paul <brianp@vmware.com>

docs/devinfo.html

@@ -172,6 +172,14 @@ Here are some examples of such a note:
   <li>NOTE: This is a candidate for the stable branches.</li>
 </ul>
 
+
+<h2>Cherry-picking candidates for a stable branch</h2>
+
+<p>
+Please use <code>git cherry-pick -x &lt;commit&gt;</code> for cherry-picking a commit
+from master to a stable branch.
+</p>
+
 <h2>Making a New Mesa Release</h2>
 
 <p>