docs: hacking: mention git-publish prominently

This tool takes care of many of the tedious parts of submitting
a patch. Mention it first, above the "manual" way using
git send-email.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>

docs/hacking.html.in

@@ -29,7 +29,11 @@
         file from zanata.</p>
       </li>
 
-      <li><p>Post patches using <code>git send-email</code>.</p>
+      <li><p>The simplest way to send patches is to use the
+        <a href="https://github.com/stefanha/git-publish"><code>git-publish</code></a>
+        tool. All libvirt-related repositories contain a config file that
+        tells git-publish to use the correct mailing list and subject prefix.</p>
+        <p>Alternatively, you may send patches using <code>git send-email</code>.</p>
         <p>Also, for code motion patches, you may find that <code>git
         diff --patience</code> provides an easier-to-read patch.
         However, the usual workflow of libvirt developer is:</p>