clang-format version numbers in the doc should omit the `.0` suffix

[owenca]

See https://clang.llvm.org/docs/ClangFormatStyleOptions.html#macros.

[llvmbot]

@llvm/issue-subscribers-clang-format

[h-vetinari]

/check-pick 3364d76

[h-vetinari]

Seems the bot is not working here for some reason...

[owenca]

It's not really necessary to backport it.