[Security] 8.19.0 release notes

[natasha-moore-elastic]

Resolves #6900: adds the 8.19.0 Security and Endpoint release notes.

Preview: 8.19

[github-actions]

A documentation preview will be available soon.

• 🔨 Buildkite builds
• 📚 HTML diff
• 📙 Preview page

Request a new doc build by commenting

• Rebuild this PR: run docs-build
• Rebuild this PR and all Elastic docs: run docs-build rebuild

_{run docs-build is much faster than run docs-build rebuild. A rebuild should only be needed in rare situations.}

_{If your PR continues to fail for an unknown reason, the doc build pipeline may be broken. Elastic employees can check the pipeline status here.}

[approksiu]

LGTM, one suggestion to working change.

[benironside]

LGTM!

[mergify]

This pull request is now in conflicts. Could you fix it @natasha-moore-elastic? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b rn-8.19.0 upstream/rn-8.19.0
git merge upstream/8.19
git push upstream rn-8.19.0

[banderror]

Rule Management notes LGTM, just posted some nits. Thank you @natasha-moore-elastic!

[yctercero]

I may have missed it, but we should also add elastic/kibana#223198 as an enhancement.

[yctercero]

I think we also discussed release noting elastic/kibana#216667 cc @vitaliidm

[natasha-moore-elastic]

I think we also discussed release noting elastic/kibana#216667 cc @vitaliidm

This one was release-noted in 8.18.1, and we generally only release-note PRs in the earliest version they apply to.

[natasha-moore-elastic]

I may have missed it, but we should also add elastic/kibana#223198 as an enhancement.

Added!