[DOCS] Add 7.15.2 release notes (#1804) (#1805)

Author: Adam Locke

docs/src/reference/asciidoc/appendix/release-notes/7.15.2.adoc

@@ -0,0 +1,5 @@
+[[eshadoop-7.15.2]]
+== Elasticsearch for Apache Hadoop version 7.15.2
+
+ES-Hadoop 7.15.2 is a version compatibility release, tested specifically against
+Elasticsearch 7.15.2.

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-7.15.2>>
 * <<eshadoop-7.15.1>>
 * <<eshadoop-7.15.0>>
 * <<eshadoop-7.14.2>>
@@ -107,6 +108,7 @@ http://github.com/elastic/elasticsearch-hadoop/issues/XXX[#XXX]
 
 ////////////////////////
 
+include::release-notes/7.15.2.adoc[]
 include::release-notes/7.15.1.adoc[]
 include::release-notes/7.15.0.adoc[]
 include::release-notes/7.14.2.adoc[]