Add elasticsearch back into the 2.14 release notes

But mention that it is experimental.

This reverts commit 1a5f3a3ecc50f8f292165c653307b69d2a5632d1.

Change-Id: Ief7f07d0cc9a382f92799df7815c18cad9e3ceb1
diff --git a/releases/2.14.md b/releases/2.14.md
index 7e3fa8e..76db7d0 100644
--- a/releases/2.14.md
+++ b/releases/2.14.md
@@ -14,6 +14,7 @@
 * Support for receiving review comments by email
 * New [Polymer](https://www.polymer-project.org/) based user interface
 * Support for elliptic curve/ed25519 SSH keys
+* Secondary index with Elastic Search (experimental)
 
 ## Important Notes
 
@@ -108,6 +109,16 @@
 Gerrit now supports
 [receiving review comments by email](http://gerrit-documentation.storage.googleapis.com/Documentation/2.14/intro-user.html#reply-by-email).
 
+### Secondary Index with Elastic Search
+
+It is possible to enable Elastic Search as a secondary index by setting
+[`index.type`](http://gerrit-documentation.storage.googleapis.com/Documentation/2.14/config-gerrit.html#index.type)
+to `ELASTICSEARCH` and configuring the
+[Elastic Search specific configuration parameters](http://gerrit-documentation.storage.googleapis.com/Documentation/2.14/config-gerrit.html#elasticsearch).
+
+Note that the Elastic Search implementation is still considered experimental
+and it is not advised to use it for production systems.
+
 ### User Interface
 
 * Tags can be created and deleted via the Tags screen in the UI.
diff --git a/releases/README.md b/releases/README.md
index 01edcd7..f85b5c2 100644
--- a/releases/README.md
+++ b/releases/README.md
@@ -24,6 +24,8 @@
 
 * Support for elliptic curve/ed25519 SSH keys
 
+* Secondary index with Elastic Search (experimental)
+
 [Release notes for Gerrit 2.14](/releases/2.14.md)
 
 ## 2.13 {#2.13}