[OPS] [DOCS] Update Kibana release notes generation tool

[leemthompo]

We want to update the Kibana release notes tool to stop using the autogenerated pattern "For the Elastic Enterprise Search X.x.x release information, refer to Elastic Enterprise Search Documentation Release notes."

I see there's this code, which overwrites the conventional logic. We simply want to remove that logic and pull the release notes in. This will obviate the need to manually grab those release notes from the PRs and update the Kibana release notes, like we did in https://github.com/elastic/kibana/pull/170108/files.

Thanks!

cc @mbondyra @mistic @delanni @chriscressman

[elasticmachine]

Pinging @elastic/kibana-operations (Team:Operations)

[jbudz]

See elastic/kibana-release-notes#10