License for documentation

["Martin Bialasinski" <martin@internet-treff.uni-koeln.de>]

Hi,

the programming language pike is licensed under the GPL and is part of 
main. The pike homepage (pike.idonex.se) has the pike documentation as
HTML files. They are not part of the pike sources.

There is a download version of the manual, but is has no license or
copyright notice neither in the text, nor in a seperate file.

I want to package the manual, so I guess I have to speak to the author 
about a license.

Is there a recommended license for documentation that lets the package
into main? Is it sufficient, if the author grants me this license for
the Debian package by mail, or has it to be part of the online
documentation and the tarball on the author's site?

Thanks for your feedback,
       Martin

[ Please Cc: me on answers ]