Standardize RST header syntax

[tetrapod00]

See #10369. Discuss and approve that PR first. As is, this PR implements the standard order of headers described in that PR:

Page title
==========

Header
------

Sub-header
~~~~~~~~~~

Sub-sub-header
^^^^^^^^^^^^^^

Sub-sub-sub-header
""""""""""""""""""

I think I found all the changes to make here, but I might have missed some pages. Since RST handles header syntax per-page, it's not a big deal to come back later and fix any pages that I mised. In each changed page here, I made sure to read through the whole page and confirm that the required changes have been made.

[tetrapod00]

This is the one "real" change here, and the source of the +1 line. It adds a space between the header and a table.

[skyace65]

I need to find time to review all of this but I'm ok with this standardization. @mhilbrunner any thoughts?

[tetrapod00]

Note that even though there are no conflicts, this is no longer good to merge as-is without going through all the pages again, due to additions within the changed pages that still use the existing set of header syntax.

[mhilbrunner]

@tetrapod00 I think this looks good and makes sense, feel free to rebase/fix and then go ahead and merge to avoid conflicts piling up again.

[tetrapod00]

I looked through the already changed pages and found two fixes to make. Additionally, I looked through recently merged new pages and updated those as well.

Since I don't expect us to merge any more large pages during this slow period, I'll wait to merge this for just a little while in case @skyace65 or anyone else wants to take another look.

[mhilbrunner]

Lets start the new year by getting this in :) Thanks!