LLVM 17.x Release Notes update

[tobiashieta]

Reminder to all developers to update and revise the release notes for LLVM 17.

In order to queue up the release notes for the release branch, follow these instructions:

• fork llvm/llvm-project on GitHub
• push your release note changes to a branch
• create a GitHub issue and add the following comment: /branch <user>/llvm-project/<branch>

Thanks!