Reference git.o.o DevStack repo rather than GitHub

In docs, use git.o.o URLs rather than GitHub URLs for the DevStack repo,
and don't mention GitHub when git.o.o is more appropriate.
Also, replaced GitHub logo with Git logo in quickstart.png.

Change-Id: Iab0006144f008963b8cb5be2d10ce0f360c0e6ca
diff --git a/doc/source/guides/multinode-lab.html b/doc/source/guides/multinode-lab.html
index 62232ef..6a5f98c 100644
--- a/doc/source/guides/multinode-lab.html
+++ b/doc/source/guides/multinode-lab.html
@@ -34,7 +34,7 @@
             <li><a href="../overview.html">Overview</a></li>
             <li><a href="../changes.html">Changes</a></li>
             <li><a href="../faq.html">FAQ</a></li>
-            <li><a href="http://github.com/openstack-dev/devstack">GitHub</a></li>
+            <li><a href="https://git.openstack.org/cgit/openstack-dev/devstack">git.openstack.org</a></li>
             <li><a href="https://review.openstack.org/#/q/status:open+project:openstack-dev/devstack,n,z">Gerrit</a></li>
           </ul>
         </div>
@@ -129,8 +129,8 @@
 echo "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCyYjfgyPazTvGpd8OaAvtU2utL8W6gWC4JdRS1J95GhNNfQd657yO6s1AH5KYQWktcE6FO/xNUC2reEXSGC7ezy+sGO1kj9Limv5vrvNHvF1+wts0Cmyx61D2nQw35/Qz8BvpdJANL7VwP/cFI/p3yhvx2lsnjFE3hN8xRB2LtLUopUSVdBwACOVUmH2G+2BWMJDjVINd2DPqRIA4Zhy09KJ3O1Joabr0XpQL0yt/I9x8BVHdAx6l9U0tMg9dj5+tAjZvMAFfye3PJcYwwsfJoFxC8w/SLtqlFX7Ehw++8RtvomvuipLdmWCy+T9hIkl+gHYE4cS3OIqXH7f49jdJf jesse@spacey.local" > ~/.ssh/authorized_keys</pre>
 
         <h3>Download DevStack</h3>
-        <p>Grab the latest version of DevStack from github:</p>
-        <pre>git clone https://github.com/openstack-dev/devstack.git
+        <p>Grab the latest version of DevStack:</p>
+        <pre>git clone https://git.openstack.org/openstack-dev/devstack
 cd devstack</pre>
 
         <p>Up to this point all of the steps apply to each node in the cluster.  From here on