Add bigtable GCPolicy resource (#4578)

Signed-off-by: Modular Magician <[email protected]>

Author: modular-magician

website/google.erb

@@ -234,6 +234,10 @@
       <a href="/docs/providers/google/r/bigtable_app_profile.html">google_bigtable_app_profile</a>
       </li>
 
+      <li<%= sidebar_current("docs-google-bigtable-gc-policy") %>>
+      <a href="/docs/providers/google/r/bigtable_gc_policy.html">google_bigtable_gc_policy</a>
+      </li>
+
       <li<%= sidebar_current("docs-google-bigtable-instance") %>>
       <a href="/docs/providers/google/r/bigtable_instance.html">google_bigtable_instance</a>
       </li>