Revert "[DOCS] Add 6.8.4 release notes (#1373)" (#1375)

This reverts commit 2e602b3.

Author: jrodewig

docs/src/reference/asciidoc/appendix/release-notes/6.8.4.adoc

@@ -8,7 +8,6 @@ This section summarizes the changes in each release.
 [float]
 [[release-notes-6]]
 ===== 6.x
-* <<eshadoop-6.8.4>>
 * <<eshadoop-6.8.3>>
 * <<eshadoop-6.8.2>>
 * <<eshadoop-6.8.1>>
@@ -97,7 +96,6 @@ http://github.com/elastic/elasticsearch-hadoop/issues/XXX[#XXX]
 
 ////////////////////////
 
-include::release-notes/6.8.4.adoc[]
 include::release-notes/6.8.3.adoc[]
 include::release-notes/6.8.2.adoc[]
 include::release-notes/6.8.1.adoc[]