Bump changelog version to 6.4 (#30217)

jasontedor · jasontedor · commit 16419e83abcc · 2018-04-27T16:22:47.000-04:00
This commit bumps the changelog version to 6.4 as now that 6.3 is
feature frozen there would be no additional entries in the changelog for
6.3.0.
diff --git a/docs/CHANGELOG.asciidoc b/docs/CHANGELOG.asciidoc
@@ -31,7 +31,7 @@ written to by an older Elasticsearch after writing to it with a newer Elasticsea
 
 === Known Issues
 
-== Elasticsearch version 6.3.0
+== Elasticsearch version 6.4.0
 
 === New Features
 
