removes gitter integration

Removes gitter integration from the documentation site.

Author: arturcic

docs/input/_Bottom.cshtml

@@ -1,10 +1,3 @@
 <div class="github-button">
     <a href="https://github.com/GitTools/GitVersion"><i class="fa fa-github"></i> GitHub</a>
 </div>
-@* disable gitter sidecar - https://github.com/matrix-org/matrix-public-archive/issues/157 *@
-@* <script>
-    ((window.gitter = {}).chat = {}).options = {
-        room: 'GitTools/GitVersion'
-    };
-</script>
-<script src="https://sidecar.gitter.im/dist/sidecar.v1.js" async defer></script> *@

docs/input/assets/css/override.less

@@ -105,10 +105,6 @@ body.layout-boxed .top-banner,
     font-size: 50px;
 }
 
-.gitter-open-chat-button {
-    background-color: @purple;
-}
-
 main {
     font-size: 2rem;
 }