[llvm] [docs][TypeProf]Update instrumentation file format document (PR #83309)

[Mingming Liu via llvm-commits]

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@@ -333,6 +342,37 @@ Function names serve as keys in the PGO data hash table when raw profiles are
 converted into indexed profiles. They are also crucial for ``llvm-profdata`` to
 show the profiles in a human-readable way.
 
+Virtual Table Profile Data
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This section is used for `type profiling`_. Each entry corresponds to one virtual
+table and could be illustrated with the following C++ struct
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minglotus-6 wrote:

done.

https://github.com/llvm/llvm-project/pull/83309