[llvm] [docs] Reword the alignment implications for atomic instructions. (PR #75871)

[Jonas Paulsson via llvm-commits]

JonPsson1 wrote:

Adding some more reviewers so that hopefully there can be some consensus around this notion whether an unaligned atomic IR instruction is undefined behavior or not. This is motivated by the fact that AtomicExpand pass always turn these into libcalls.

https://github.com/llvm/llvm-project/pull/75871