Change footnotes to specific numbering for permissions tables

What does this MR do?

Following up from !79614 (merged), there was one footnote that was no longer needed for the main permissions table, and the table itself was no longer aligned. I first aligned the table columns again.

Then I realized that we could drastically improve the maintainability of the footnotes if we allow specific numbering in the list, by turning off that markdownlint rule for those footnotes. This still renders normally, but it means that maintainers will have a much easier time determining which footnote relates to which table cell when looking at the unrendered markdown.

So the full list of changes:

• Align column cells.
• Remove one footnote (was (*3*) formerly).
• Renumber the footnotes lists to specific numbers.
• Renumber all the footnote mentions to match the updated lists.

Related issues

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