[DOCS] Add 7.16.3 release notes (#1848)

Author: jrodewig

docs/src/reference/asciidoc/appendix/release-notes/7.16.3.adoc

@@ -0,0 +1,7 @@
+[[eshadoop-7.16.3]]
+== Elasticsearch for Apache Hadoop version 7.16.3
+
+coming::[7.16.3]
+
+ES-Hadoop 7.16.3 is a version compatibility release, tested specifically against
+Elasticsearch 7.16.3.

docs/src/reference/asciidoc/appendix/release.adoc

@@ -9,6 +9,7 @@ This section summarizes the changes in each release.
 [[release-notes-7]]
 ===== 7.x
 
+* <<eshadoop-7.16.3>>
 * <<eshadoop-7.16.2>>
 * <<eshadoop-7.16.1>>
 * <<eshadoop-7.16.0>>
@@ -111,6 +112,7 @@ http://github.com/elastic/elasticsearch-hadoop/issues/XXX[#XXX]
 
 ////////////////////////
 
+include::release-notes/7.16.3.adoc[]
 include::release-notes/7.16.2.adoc[]
 include::release-notes/7.16.1.adoc[]
 include::release-notes/7.16.0.adoc[]