Remove 7.0.0 from 6.x changelog
This commit removes 7.0.0 entires from the changelog for the 6.x branch.
= Elasticsearch Release Notes
-== Elasticsearch 7.0.0
-
-=== Breaking Changes
-
-=== Breaking Java Changes
-
-=== Deprecations
-
-=== New Features
-
-=== Enhancements
-
-=== Bug Fixes
-
-=== Regressions
-
-=== Known Issues
-
== Elasticsearch version 6.3.0
=== New Features
