Add "Try in Docker" button

Author: deniszh

quick-start-guides/index.html

@@ -39,5 +39,9 @@ <h2>Quick Start Guides</h2>
         <h2>Install Graphite and Get Started</h2>
         <a class="btn btn--primary" href="https://graphite.readthedocs.io/en/latest/install.html" target="_blank">Install</a>
     </div>    
+    <div class="text-center">
+        <h2>or try Graphite in Docker and have it running in seconds</h2>
+        <a class="btn btn--primary" href="https://graphite.readthedocs.io/en/latest/install.html#docker" target="_blank">Try Graphite in Docker </a>
+    </div>
   </div>
 </div>