[DOCS] 7.17.4 Release Notes

[nastasha-solomon]

Description

Generate the 7.17.4 release notes and publish them before or on the release day, which is May 3, 2022.

Set up the release notes file

1. Check out the 7.17 branch.
2. Run a git fetch origin then git pull to pull in the latest changes.
3. Create a branch for the release notes, for example, issue-XXX-7.17.4-rn.
4. Add release notes to the 7.17 asciidoc file.
5. Add a link to the 7.17.4 release notes to update the release note's index page. Should be:
   <<release-notes-7.17.4, {elastic-sec} version 7.17.4>>
6. Open a PR and switch the base branch (which is the PR will merge into) from main to 7.17.
7. Complete the technical and editorial review, then merge the PR to 7.17.

[nastasha-solomon]

Closing as #1898 has been merged.