Add new documentation about the pre-commit hook

[kaixin-hc]

Fixes #9063

Aside from updating the specific sections flagged in the issue, I moved the pre-commit hook from under the manual install to above the manual install for clang-format. My thought process was that the new pre-commit workflow automatically installs the right version of clang-format; since that seems to be an issue warranting a note in the manual install section, rearranging it such that the pre-commit recommendation is suggested first made sense to me.

[kaixin-hc]

@AThousandShips @mhilbrunner

Seeing @Chubercik 's PR updating to remove references to Black, shall we KIV the formatting question around if black should be formatted or capitalised? To be consistent I've returned all clang-format mentions to be unformatted as well. Let me know if there's anything else I can do!

[mhilbrunner]

Yeah, I don't think that matters too much or has the highest priority right now. We should get this merged so people have docs they can look at for the change (and thanks for taking care of it).

Would be nice if you could squash the commits if you feel comfortable with that.

I'll see if I can get Rémi to review this on monday as he IIRC implemented the change and may spot stuff I don't, otherwise, I'll just merge as is :) Thanks again!

[kaixin-hc]

Squashed it! Thanks for the reminder and sorry for missing it :)

[AThousandShips]

Thank you! And congratulations on your first merged contribution! 🎉