ping(8): Fix typo in ping6.c
Line 703 & 863: kerel -> kernel
Line 2110: resposne -> response
Event: Advanced UNIX Programming Course (Fall’23) at NTHU.
Pull Request: https://github.com/freebsd/freebsd-src/pull/967
(cherry picked from commit e9866ce84f41bf8a5122713b027d1af05cbbb5b3)