[DOCS] Added security fix to 6.6.1 RNs. (#39129)

* [DOCS] Added security fix to 6.6.1 RNs.

* [DOCS] Bumped doc version for 6.6.1.

Author: debadair

docs/Versions.asciidoc

@@ -1,4 +1,4 @@
-:version:               6.6.0
+:version:               6.6.1
 :major-version:         6.x
 :lucene_version:        7.6.0
 :lucene_version_path:   7_6_0

docs/reference/release-notes/6.6.asciidoc

@@ -2,8 +2,6 @@
 [[release-notes-6.6.1]]
 == {es} version 6.6.1
 
-coming[6.6.1]
-
 Also see <<breaking-changes-6.6, Breaking changes in 6.6>>.
 
 [[enhancement-6.6.1]]
@@ -71,6 +69,8 @@ Search::
 * Use executor `SAME` to handle search related handlers {pull}37427[#37427] (issues: {issue}33732[#33732], {issue}37392[#37392])
 
 Security::
+* Fix an improper permission issue when a new name is attached to an index. (CVE-2019-7611). See
+https://www.elastic.co/community/security[Security issues].
 * Fix potential NPE in UsersTool {pull}37660[#37660]
 
 ZenDiscovery::