Merge pull request #4790 from vespa-engine/bratseth/gcp-us-east

Add gcp-us-east

Author: bratseth

en/operations/zones.html

@@ -72,6 +72,7 @@
     <tr><td><a href="environments.html#prod">prod</a><td>gcp-us-central1-b</td><td></td></tr>
     <tr><td><a href="environments.html#prod">prod</a><td>gcp-us-central1-c</td><td></td></tr>
     <tr><td><a href="environments.html#prod">prod</a><td>gcp-us-central1-f</td><td></td></tr>
+    <tr><td><a href="environments.html#prod">prod</a><td>gcp-us-east4-c</td><td></td></tr>
     <tr><td><a href="environments.html#prod">prod</a><td>gcp-us-west1-c</td><td></td></tr>
   </tbody>
 </table>