[llvm] [docs][GitHub] Document alternative approach to stacked PRs (PR #132424)

[Andrzej Warzyński via llvm-commits]

banach-space wrote:

Hey @boomanaiden154 — thanks again for all the thoughtful discussion and suggestions so far!

I’ve refactored this to align with your feedback. The current version outlines three different ways of handling stacked PRs, with the goal of documenting the approaches currently in use.

I understand you’re not particularly fond of the first approach:

> That's not a very good way to do it, at least in my opinion.

Before recommending one method over the others, I’d like to give each some visibility and see if clear preferences emerge. If so, I’m happy to reflect that in the docs — possibly in a follow-up PR.

Let me know what you think!

https://github.com/llvm/llvm-project/pull/132424