Only between podman-build, create, and run. podman-pod-create
is too different.
As usual I went with the podman-run version. This means
keeping the word "flag" (which should be "option"), for
ease of review. I will fix in my in-progress cleanup PR.
For podman-build, I removed "during the build" and changed
it to a note for that man page only.
Signed-off-by: Ed Santiago <santiago@redhat.com>