Encourage newcomers to create PRs with updated documentation when it's missing for them

[kbeyls]

At the EuroLLVM 2024 community.o workshop, many newcomers point out that a lot of areas in LLVM are underdocumented. The backend was highlighted as especially lacking.

One idea we had was that maybe the best way to improve documentation is that when the documentation isn't good enough for what you need to work on; you (as a newcomer) should write up a pull request with documentation describing how you think how it works. Even if it's wrong, that's the best way to get the people with more experience to point you in the right direction. And as a side-effect, the project's documentation improves. This should be documented clearly as a "the most powerful way to get the documentation you need to be created".

Of course, this is at odds with newcomers often feeling "social anxiety" to do anything publicly.

How could we help overcome this?