Adds 6.4.3 release notes

Author: colings86

docs/reference/release-notes/6.4.asciidoc

@@ -34,6 +34,35 @@
 //=== Known Issues
 ////
 
+[[release-notes-6.4.3]]
+== 6.4.3 Release Notes
+
+coming[6.4.3]
+
+Also see <<breaking-changes-6.4>>.
+
+[[bug-6.4.3]]
+[float]
+=== Bug fixes
+
+Authentication::
+* ListenableFuture should preserve ThreadContext {pull}34394[#34394]
+* Allow an AuthenticationResult to return metadata {pull}34382[#34382] (issues: {issue}34290[#34290], {issue}34332[#34332])
+* Preserve thread context during authentication  {pull}34290[#34290]
+
+Circuit Breakers::
+* Make accounting circuit breaker settings dynamic {pull}34372[#34372] (issue: {issue}34368[#34368])
+
+Java High Level REST Client::
+* HLRC: Fixing bug when getting a missing pipeline {pull}34286[#34286] (issue: {issue}34119[#34119])
+
+Network::
+*  Support PKCS#11 tokens as keystores and truststores  {pull}34063[#34063] (issue: {issue}11[#11])
+* Correctly handle PKCS#11 tokens for system keystore {pull}33460[#33460] (issues: {issue}11[#11], {issue}33459[#33459])
+
+Security::
+* Security: use x-pack config files when present {pull}33688[#33688] (issue: {issue}33464[#33464])
+
 [[release-notes-6.4.2]]
 == {es} version 6.4.2