REST API: Improve the `rest_*_collection_params` filter docs and fix the terms filter.

The `rest_{$taxonomy}_collection_params` filter in 4.7 is incorrectly using
single quotes instead of double quotes, which means it is not working correctly
as a dynamic filter.  This fixes the quotes around the filter name, and also
updates the docblocks for the other 3 similar filters for better conformance to
the documentation standards.

Props shazahm1hotmailcom, JPry, jnylen0.
Fixes #39300.

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