Documentation: Vulnerability Dismissal Types / Reasons

Documentation issue for adding Dismissal Types to the vulnerability page

https://docs.gitlab.com/ee/user/application_security/vulnerabilities/

Note:

This project will be available on .com when it's ready, but can not go to self-managed until the Vulnerabilities Feedback Deprecation is enabled by default. Our docs should clarify this so self-managed users know it isn't available yet.

Example of showing where a feature is available: https://docs.gitlab.com/ee/user/application_security/sast/#automatic-vulnerability-resolution