[llvm] [llvm][docs] Correct the list of the available -fveclib= options to match with the reality (PR #168205)

[Kiran Chandramohan via llvm-commits]

https://github.com/kiranchandramohan approved this pull request.

Updating the documentation to show the correct values that are accepted makes sense to me. Any further work should be taken up in a separate patch by interested parties after writing an RFC in discourse.

LGTM. Please wait for a reviewer from Clang Driver/LLVM vectorizer.

https://github.com/llvm/llvm-project/pull/168205