look(1): Correct the example's description
Remove an extra 'e' in the example command. It is a prefix, not a typo.
This is from the Advanced UNIX Programming Course (Fall’23) at NTHU.
MFC after: 3 days
Pull Request: https://github.com/freebsd/freebsd-src/pull/913
(cherry picked from commit 7df526eb10c9095e4988e77900f60ba00c42b095)