Remove references to AFS Product Support in -oktozap

Remove references to AFS Product Support in -oktozap

salvager and salvageserver's documentation of -oktozap says to not use
without consultation with AFS Development or Product Support, left over
from the IBM product.  Remove those references and add a caution more
in line with open source.

Change-Id: I136dc145caf3e8e3a992c239e1a46d86f96580ed
Reviewed-on: http://gerrit.openafs.org/2030
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>