[DOCS] Add 7.5.0 release notes (#1390)

Author: jrodewig

docs/src/reference/asciidoc/appendix/release-notes/7.5.0.adoc

@@ -0,0 +1,6 @@
+[[eshadoop-7.5.0]]
+== Elasticsearch for Apache Hadoop version 7.5.0
+December 2, 2019
+
+ES-Hadoop 7.5.0 is a version compatibility release,
+tested specifically against Elasticsearch 7.5.0.

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

@@ -8,6 +8,7 @@ This section summarizes the changes in each release.
 [float]
 [[release-notes-7]]
 ===== 7.x
+* <<eshadoop-7.5.0>>
 * <<eshadoop-7.4.2>>
 * <<eshadoop-7.4.1>>
 * <<eshadoop-7.4.0>>
@@ -74,6 +75,7 @@ http://github.com/elastic/elasticsearch-hadoop/issues/XXX[#XXX]
 
 ////////////////////////
 
+include::release-notes/7.5.0.adoc[]
 include::release-notes/7.4.2.adoc[]
 include::release-notes/7.4.1.adoc[]
 include::release-notes/7.4.0.adoc[]