add Canonical acronyms and terms to spelling exceptions

[akcano]

This adds acronyms and terms mined from our glossaries as two separate sublists in wordlist.txt for convenience.

• Have you updated CHANGELOG.md with relevant file changes?
• Have you updated the documentation for this change?

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[SecondSkoll]

This should be going into canonical/praecepta where the global rules and wordlist are defined.

Edit: Well... Actually this is used as well. Do you think it's better to have it here and to merge the wordlist from there to here? The list should be in a single place.

[akcano]

TBH I'd drop the current HTML-based spellcheck altogether (I actually tried to do so previously but failed because reasons). Syndicating it from here doesn't seem sustainable or warranted; let's just add the lists there as well.

[SecondSkoll]

The way Vale works is that it will convert to HTML to check things as well, to check classes and scopes. It doesn't use Sphinx though, so it's definitely better.

Good plan, lets add it to both, then single source once pyspelling is removed.