[libc] Fix typo in header generation docs.

Reviewers: sivachandra, abrachet

Reviewed By: sivachandra, abrachet

Subscribers: libc-commits, MaskRay, tschuett

Tags: #libc-project, #llvm

Differential Revision: https://reviews.llvm.org/D72248

GitOrigin-RevId: 3101def8472a8d6007fc35d23008bbb1c0e7d39c
1 file changed