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

[David Li via llvm-commits]

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@@ -455,6 +497,16 @@ Temporal Profile Traces
 The section is used to carry on temporal profile information from raw profiles.
 See `temporal profiling`_ for the design.
 
+Virtual Table Names
+^^^^^^^^^^^^^^^^^^^^
+This section is used to carry on the names of vtables from raw profiles into
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david-xl wrote:

is used to store the names of vtables from raw profile in the index profile

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