Update 2.13.6 release notes

Change-Id: If37d888baa71f40a57f0869e79c3af2705c08287
diff --git a/releases/2.13.md b/releases/2.13.md
index b3a3c78..fb69ff0 100644
--- a/releases/2.13.md
+++ b/releases/2.13.md
@@ -473,22 +473,42 @@
 to set values in the `secure.config` file when a secure store implementation
 is used.
 
+* Allow plugins to define their own prefix for metrics reporting.
+
+  By setting `plugin.name.metricsPrefix` plugins can set the root
+  name under which their metrics are reported.
+
 * Allow HTTP password when using LDAP and basic authentication.
 
   It was not possible to use HTTP password to validate git over
   HTTP and REST API requests if LDAP was used along with HTTP basic
   authentication.
 
-* [Issue 5206](https://bugs.chromium.org/p/gerrit/issues/detail?id=5206):
-Fix display of username in `show-queue` output for git over HTTP tasks.
+* Allow callers to define notify handling when adding reviewers to a
+  change by REST API.
+
+* [Issue 4563](https://bugs.chromium.org/p/gerrit/issues/detail?id=4563):
+Only send one email when reviewers are added to a change in bulk.
 
 * [Issue 5237](https://bugs.chromium.org/p/gerrit/issues/detail?id=5237):
 Don't truncate long lines in diff screens.
 
+* [Issue 5298](https://bugs.chromium.org/p/gerrit/issues/detail?id=5298):
+Fix history token in Groups screen's "Members" tab.
+
+* [Issue 4848](https://bugs.chromium.org/p/gerrit/issues/detail?id=4848):
+Upgrade postgresql JDBC driver to 9.4.1211.jre7 to fix memory leaks.
+
+* Fix garbled text with Unicode display names obtained from HTTP headers.
+
+* Make error message for rejecting Egit placeholder Change-Id consistent.
+
 * Fix naming and prompt message for password entry in init steps.
 
 * Fix Gitweb review link generation.
 
+* Hooks plugin: emit metrics for hook execution latency, count, and errors.
+
 * Submodule fixes
 
     * Don't use fast-forward to update submodule subscription when superproject