Clarify pkg.installed pkg_verify documentation
Clarify pkg.installed pkg_verify documentation

There have been misunderstandings what the pkg_verify parameter does and
bug reports that it does not work, based on the wrong assumption that
this parameter changes the installation of new packages. The docstring
also stated that it was only provided by `yum`, but `zypper` also
provides this feature (actually it is `rpm` itself in both cases that
does the verification check)

Related issue: https://github.com/saltstack/salt/issues/44878

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt