This metric previously existed for backwards compatibility reasons
although the suggest stats were folded into search stats. This metric
was deprecated in 6.3.0 and this commit removes them for 7.0.0.
The name of the bulk thread pool was renamed to "write" with "bulk" as a
fallback name. This change was made in 6.x for BWC reasons yet in 7.0.0
we are removing this fallback. This commit removes this fallback for the
write thread pool.
* Add a CHANGELOG file for 7.x release notes.
* update file to include 6.x
* remove confusing comment and small edit to section title
* moving CHANGELOG file under docs directory, as it pertains to release notes.
