Update information about Elasticsearch support

6.5 is supported from 2.15.8 and 2.16.1. This was mentioned in the
2.16.1 release notes but mentioned a minor release which gave the
impression that the major release was already supported. Only the
client library upgrade was mentioned in the 2.15.8 release notes.

Also update the compatibility matrix with this information, and add
support for 6.6 which was added in 2.15.10.

Change-Id: I00f0fd9ee83999222aacf63a7b8d3b380762a7a9
diff --git a/pages/site/elasticsearch.md b/pages/site/elasticsearch.md
index 464aab8..66956c3 100644
--- a/pages/site/elasticsearch.md
+++ b/pages/site/elasticsearch.md
@@ -16,7 +16,8 @@
 | 6.2.x                 | 2.14.8 or 2.15.3       |
 | 6.3.x                 | 2.14.10 or 2.15.3      |
 | 6.4.x                 | 2.14.12 or 2.15.4      |
-| 6.5.x                 | 2.15.8                 |
+| 6.5.x                 | 2.15.8 or 2.16.1       |
+| 6.6.x                 | 2.15.10                |
 
 Note that although Elasticsearch 2.4.x is supported, we do not recommend using
 such an old version.
diff --git a/pages/site/releases/2.15.md b/pages/site/releases/2.15.md
index 320e9c3..80d5087 100644
--- a/pages/site/releases/2.15.md
+++ b/pages/site/releases/2.15.md
@@ -509,6 +509,9 @@
   In some cases the private and work-in-progress status indicator for
   changes updated by push was shown incorrectly.
 
+* [Issue 10038](https://bugs.chromium.org/p/gerrit/issues/detail?id=10038):
+Add support for Elasticsearch 6.5.
+
 * [Issue 9768](https://bugs.chromium.org/p/gerrit/issues/detail?id=9768):
 Explicitly set the number of shards and replicas for Elasticsearch, and
 allow them to be configured.
diff --git a/pages/site/releases/2.16.md b/pages/site/releases/2.16.md
index 5fe476c..9d430c2 100644
--- a/pages/site/releases/2.16.md
+++ b/pages/site/releases/2.16.md
@@ -723,7 +723,7 @@
 Fix failure to upgrade schema when migrating from 2.13.
 
 * [Issue 10038](https://bugs.chromium.org/p/gerrit/issues/detail?id=10038):
-Add support for Elasticsearch 6.5.1.
+Add support for Elasticsearch 6.5.
 
 * [Issue 10052](https://bugs.chromium.org/p/gerrit/issues/detail?id=10052):
 Fix invalid requests to Elasticsearch.