[llvm] [compiler-rt] [docs][IRPGO]Document two binary formats for IRPGO profiles (PR #76105)

[Mingming Liu via llvm-commits]

minglotus-6 wrote:

thanks for all the reviews! I'll wait a little bit more for review comments, and plan to submit it in early Wednesday if the pull request looks good.

p.s. I'm likely late in the party..  just realized Github UI displays rich diff (like https://github.com/llvm/llvm-project/pull/76105/files?short_path=b1805ae#diff-b1805ae3bd5b5cf0c69249b7df329ef8dd7cbfe322ae004c61f4bd507d2a87e6) with a click for review, which means the [workaround](https://github.com/llvm/llvm-project/pull/76105#issue-2051391300) is not necessary.

https://github.com/llvm/llvm-project/pull/76105