add governance to nav bar

Author: bishabosha

_data/nav-header.yml

@@ -8,5 +8,7 @@
   url: https://index.scala-lang.org
 - title: Community
   url: https://www.scala-lang.org/community/
+- title: Governance
+  url: https://www.scala-lang.org/governance/
 - title: Blog
   url: https://www.scala-lang.org/blog/