[libcxx-commits] [libcxx] [libc++] Document the strengthened noexcept convention (PR #203869)

[Louis Dionne via libcxx-commits]

ldionne wrote:

And if we decide not to officially do this after all, we would instead rip those comments out of `<expected>` so we're consistent everywhere.

https://github.com/llvm/llvm-project/pull/203869