[flang-commits] [clang] [flang] [flang][docs] Update the `-Ofast` description in `FlangDriver.md` (PR #180138)

[Kiran Chandramohan via flang-commits]

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

Thanks @s-watanabe314. LGTM.

https://github.com/llvm/llvm-project/pull/180138