Clarify in the man page that podman-search is not generally realiable
way of determining the presence/existence of an image. The results of
the v1 and the v2 endpoints depend on the implementation of each
registry; the semantics are not really specified. Some registries may
not support search at all as it's not part of the OCI dist spec.
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1978556
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>