Add Matrix URl to footer (#79)

Author: sahilister

index.html

@@ -131,6 +131,7 @@ <h2 class='uk-margin-remove-bottom'><img style='width:40px'
             <p>
               <a href='https://wiki.openstreetmap.org/wiki/India' target="_blank">Wiki</a> |
               <a href='https://t.me/OSMIndia' target="_blank">Telegram</a> |
+              <a href='https://matrix.to/#/#osm-in-general:matrix.org' target="_blank">Matrix</a> |
               <a href='https://github.com/osm-in/openstreetmap.in/' target="_blank">Github</a> |
               <a href='https://en.osm.town/@OSMIndia' rel='me' target="_blank">Mastodon</a> |
               <a href='https://twitter.com/osm_in' target="_blank">Twitter</a>