Clean up merge request approvals API page

What does this MR do?

In Update documentation for selective code owner r... (!96550 - merged) I noticed changes were being applied to a table that wasn't in alphabetical order. When I looked more closely at the page, I saw lots of small things to clean up.

Taken as a whole, this merge request looks more painful to review than it actually is. If you look one commit at a time, you'll see I batched changes of a particular type together in a single commit to make reviews easier:

1. !96798 (c9cac4e4) removes long spaces at the end of table rows.
2. !96798 (0ea092eb) strips outdated version information.
3. !96798 (c4e2fad3) re-sorts the table data into a modified alphabetical order. I put the (likely) primary key of the table first (it's usually really easy to tell, it's almost always id) and then the rest of the fields in alphabetical order
4. !96798 (15defa65) tidies up the contents of individual rows. Fix capitalization, standardize punctuation, spell out words. Most importantly: lightly edit a couple of deprecation lines to match the string GitLab 12.x (instead of just version 12.x) so these lines will be flagged by Vale in the future.
5. !96798 (f6528279) moves required parameters to the top of each table in alphabetical order

I need to make a follow-up issue regarding item 4 to ask someone in groupsource code to tell me if those GitLab 12.x deprecation lines can be removed entirely. I can't tell and it's out of scope of this merge request anyway.

Related issues

• Related to !96550 (merged) where the need was spotted
• Closes Follow-up from "Update documentation for select... (#372334 - closed)

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