Updates description of dast related yml files
What does this MR do and why?
Update the description in the 12 dast_*.yml files.
Please refer to the issue #359345 (closed) for more details.
Note:
I have copied most of the details from COMMENT ON TABLE
section of https://gitlab.com/gitlab-org/gitlab/-/blob/master/db/structure.sql the rest from gitlab document.
Edited by Aditya Tiwari