[llvm] [QualGroup] Add slides and documentation updates after July 2025 sync-up (PR #147196)

[Nikita Popov via llvm-commits]

nikic wrote:

I don't think that llvm/docs is an appropriate place to commit slides. I'd expect these to live in llvm-www, just like all the dev meeting slides.

https://github.com/llvm/llvm-project/pull/147196