[clang] Fix documentation on PGO/coverage related options. (PR #73845)

[Petr Hosek via cfe-commits]

================
@@ -4401,13 +4415,21 @@ Execute ``clang-cl /?`` to see a list of supported options:
                               Instrument only functions from files where names don't match all the regexes separated by a semi-colon
       -fprofile-filter-files=<value>
                               Instrument only functions from files where names match any regex separated by a semi-colon
-      -fprofile-instr-generate=<file>
-                              Generate instrumented code to collect execution counts into <file>
+      -fprofile-generate=<dirname>
+                              Generate instrumented code to collect execution counts into a raw profile file in the directory specified by the argument. The filename uses the %m format. See :ref:`Profiling With Instrumentation <prof_instr>`  section for details.
----------------
petrhosek wrote:

Should the second sentence say "The filename uses the default_%m.profraw."?

https://github.com/llvm/llvm-project/pull/73845