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

[Mingming Liu via llvm-commits]

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minglotus-6 wrote:

I updated filename to `InstrProfileFormat.rst` in a standalone local commit.

The actual changes should be visible in the commit right before it.

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