Add troubleshooting docs and note about annotation-value-word-blocklist

What does this MR do?

Add troubleshooting docs and note about annotation-value-word-blocklist

In GitLab 15.6 - we added a recommended annotation-value-word-blocklist in order to mitigate CVE-2021-25742, this has caused some upgrade problems for GitLab users, and this adds a troubleshooting section and background information for GitLab administrators.

Changelog: added

Related issues

Fixes Some ingresses gone 404 upon upgrading to 15.6 ... (#4021 - closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.