Add vulnerability related issues documentation

What does this MR do?

This MR adds documentation for the related issues block on the standalone vulnerabilities page, and sets up the link to the documentation. This MR is a follow-up of this MR: !35625 (merged) and was broken out to reduce the MR size.

How to test locally

https://gitlab.com/snippets/1956676

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• [-] Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done