Docs: add words to disallowed word list

What does this MR do?

• Adds Postgres to the disallowed word list in Vale, requiring PostgreSQL instead.
• Adds param and params to the disallowed word list, requiring parameter and parameters instead.

No pages in this repo were currently using these words.

Related to gitlab!27764 (merged) where we're doing the work in another repository as well.

Related to gitlab#211983 (closed) where several substitution pairs are being tracked.

Moving docs to a new location?

• Make sure the old link is not removed and has its contents replaced with a link to the new location.
• Make sure internal links pointing to the document in question are not broken.
• Search and replace any links referring to old docs in GitLab Runner's source code