Update wishlist now that the -hostkey option exists.

Apparently there wasn't already a wishlist entry for the option, which
surprises me. I've written one, and also updated 'accept-host-keys' to
mention it as an alternative to pre-adding things in the registry.


git-svn-id: svn://svn.tartarus.org/sgt@10221 cda61777-01e9-0310-a592-d414129be87e