[llvm] [llvm][docs] Minor fixes and improvements for release process (PR #151956)

[Cullen Rhodes via llvm-commits]

https://github.com/c-rhodes commented:

Just a few things I noticed going through the doc Tobias pointed me at. I also had a couple of other questions/observations.

1. I noticed http://prereleases-origin.llvm.org is updated a bit inconsistently and hasn't been updated since Feb 24, is this step still necessary? https://github.com/llvm/llvm-project/blob/1406058cbacc8720042eed15a087f8ff1b5c5e1c/llvm/docs/HowToReleaseLLVM.rst?plain=1#L407
2. https://github.com/llvm/llvm-project/blob/1406058cbacc8720042eed15a087f8ff1b5c5e1c/llvm/docs/HowToReleaseLLVM.rst?plain=1#L362-L363 - what's the demo page? Also I think it'd be helpful to expand on what docs need updating.

Happy to fix these if you can give me some pointers.

https://github.com/llvm/llvm-project/pull/151956