Start release notes for 2.15.15

Change-Id: I7582c5eb384c62d989b8c7400f617db709517697
diff --git a/pages/site/releases/2.15.md b/pages/site/releases/2.15.md
index b9273de..5cb586f 100644
--- a/pages/site/releases/2.15.md
+++ b/pages/site/releases/2.15.md
@@ -406,7 +406,7 @@
 
 * Update Jetty to 9.3.18.v20170406 (updated to 9.3.24.v20180605 in 2.15.7)
 
-* Update JGit to 4.9.0.201710071750-r (updated to 4.9.10.201904181027-r in 2.15.13)
+* Update JGit to 4.9.0.201710071750-r (updated to 4.11.8.201904181247-r in 2.15.15)
 
 * Update Joda-Time to 2.9.9
 
@@ -422,6 +422,76 @@
 
 ## Bugfix Releases
 
+### 2.15.15
+
+* Upgrade JGit to 4.11.8.201904181247-r.
+
+  This version of JGit includes a fix in the resolve merger to handle conflicts
+  in submodules. See [the upstream issue](https://bugs.eclipse.org/bugs/show_bug.cgi?id=494551)
+  for details.
+
+* [Issue 10664](https://bugs.chromium.org/p/gerrit/issues/detail?id=10664):
+Fix duplicate key detection in MySQL patch review database.
+
+* [Issue 10763](https://bugs.chromium.org/p/gerrit/issues/detail?id=10763):
+Fix ACLs to allow regexes for tag and ref permissions.
+
+  The documentation states that reference names can also be described with
+  a regular expression by prefixing the reference name with `^`, but the UI
+  only showed the creation field when a non-regex name was used.
+
+* [Issue 10499](https://bugs.chromium.org/p/gerrit/issues/detail?id=10499):
+Set default number of shards according to Elasticsearch version.
+
+  In Elasticsearch version 7.0 the default number of shards was reduced from
+  5 to 1.
+
+  See the [Elasticsearch documentation](https://www.elastic.co/guide/en/elasticsearch/reference/current/getting-started-concepts.html#getting-started-shards-and-replicas)
+  for details.
+
+* Allow commit validation listeners to ignore the `skip-validation` push option.
+
+  Gerrit allows certain users to skip validation of new commits by passing
+  the `skip-validation` push option.
+
+  A new method `shouldValidateAllCommits` is added on the
+  `CommitValidationListener`, to allow plugin implemented validators to
+  override this option and always be invoked for new commits. The new
+  method has a default implementation that returns `false` meaning that
+  existing implementations don't need to be modified and will behave the
+  same as before.
+
+* Optimize commit and ref operation validation for non-ff push.
+
+  On a non-ff push all the commits were validated before the ref operation
+  was validated. On a push with many commits, validating all the commits is
+  wasteful in the case where the ref operation is rejected. The logic is
+  changed so that the ref operation validation is performed before the commit
+  validation.
+
+* Disallow change index task duplication.
+
+  It was possible for multiple index tasks to be queued for the same change.
+
+* Fix error message when JRE is not found when starting Gerrit.
+
+  The error message recommended to check for a JRE ">= 1.7", but Gerrit requires
+  Java 8 minimum.
+
+* Expose the `createProject` method of the `CreateProject` class to plugins.
+
+  This allows plugins to directly invoke the project creation, avoiding the
+  checks that are performed when invking via the `apply` method.
+
+* PolyGerrit UI fixes:
+
+  * Fix hiding the HTTP password screen.
+
+    It was possible for the HTTP password to be un-hidden using CSS.
+
+  * Add an extension point to allow adding links to the user header.
+
+
 ### 2.15.14
 
 * Allow to disable log file rotation and compression.