[llvm] [compiler-rt] [docs][IRPGO]Document two binary formats for instrumentation-based profiles, with a focus on IRPGO. (PR #76105)

[Fangrui Song via llvm-commits]

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@@ -123,6 +123,8 @@ INSTR_PROF_VALUE_NODE(PtrToNodeT, llvm::PointerType::getUnqual(Ctx), Next, \
 
 /* INSTR_PROF_RAW_HEADER  start */
 /* Definition of member fields of the raw profile header data structure. */
+/* Please update https://llvm.org/docs/InstrProfileFormat.html as appropriate
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MaskRay wrote:

`llvm/docs/InstrProfileFormat.rst`


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