add scala ambassadors to the footer (#3033)

Author: bishabosha

_data/footer.yml

@@ -23,6 +23,8 @@
       url: "http://scala-lang.org/community/"
     - title: Governance
       url: "http://scala-lang.org/community/index.html#governance"
+    - title: Scala Ambassadors
+      url: "http://scala-lang.org/ambassadors/"
     - title: Mailing Lists
       url: "http://scala-lang.org/community/index.html#mailing-lists"
     - title: Chat Rooms & More