[llvm] [Github] Add Pull Request template with links to Github docs/Discord/Forums (PR #71923)

[David Spickett via llvm-commits]

DavidSpickett wrote:

On the assumption that llvm-project has changed the default squash and merge to "Default to pull request title and description" (which matches what I've seen), all the text from the PR template is included however you merge it. There is no way to automatically remove it.

(https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/configuring-pull-request-merges/configuring-commit-squashing-for-pull-requests)

So doing this as a PR template isn't going to work, and on second thought is not the best place for this information anyway. I will look into this being a bot comment for new users instead (or anyone without write permissions?).

@tstellar do you know where llvm-bot's code is? Is it possible to run an instance of it on your own fork?

https://github.com/llvm/llvm-project/pull/71923