Run: correct a typo in the --cap-add help text
Run: correct a typo in the --cap-add help text

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>

Closes: #1721
Approved by: rhatdan

nalind/buildah-1,projectatomic/buildah,rhatdan/buildah,rhatdan/buildah,nalind/buildah,rhatdan/buildah,TomSweeneyRedHat/buildah,nalind/buildah,TomSweeneyRedHat/buildah,projectatomic/buildah,nalind/buildah-1,projectatomic/buildah,TomSweeneyRedHat/buildah,nalind/buildah-1