[krbdev.mit.edu #7608] improve kadmin manpage "-e" description

[Tom Yu via RT]

On the #kerberos IRC channel earlier today:

12:52 <tlyu> Pegasus_RPG: the page as is mentions enc:salt... how should we
             make it more clear?
12:53 <Pegasus_RPG> tlyu: add an example, like   "enc:salt   e.g.
                    arcfour-hmac:normal"
12:54 <Pegasus_RPG> or provide a link to the salt types like you do the enctypes

We might also want a section describing the enc:salt list and what is
valid syntax for those (e.g., spaces or commas).