Update faq.rst

[chr-b]

Added information on Elasticsearch user authorization.

Description

Extend the FAQ with troubleshooting information related to Elasticsearch role-base access control.

Checklist

• I have reviewed the contributing guidelines.
• I have included unit tests for my changes or additions.
• I have successfully run make test-docker with my changes.
• I have manually tested all relevant modes of the change in this PR.
• I have updated the documentation.
• I have updated the changelog.

Questions or Comments

This is a pure documentation update

[jertel]

Thanks for helping improve the docs, it's very much appreciated. When you have a minute please add the changelog entry. You'll see another [Docs] update from the TBD section that you can use as a template.

[chr-b]

Thanks for helping improve the docs, it's very much appreciated. When you have a minute please add the changelog entry. You'll see another [Docs] update from the TBD section that you can use as a template.

Done