[tldoc] documentation license?

[Karl Berry]

    But anything that's approved by the Open Source Initiative is fine with me

They don't mention public domain, but I assume it's ok.  If not, they're
insane.

I should have mentioned this before -- one principal reason that I want
to use public domain is that if we use any other license at all, we have
to figure out (and maintain) who the copyright holders are.  I really
don't want to do that, which will be very time consuming and have no
actual benefit to TeX users.

So far no one has objected to public domain, so I am hopeful :).