The skalibs source code from skalibs is released under the ISC license, the text of which can be found in the COPYING file enclosed in the package.
The license has been chosen for its simplicity - it's short and to the point - and above all its permissivity. There is nothing legitimate you should not be able to do with the skalibs code. If the license somehow stands in the way, please let me know.
However, the skalibs documentation, which you are currently reading, and which is available in the doc/ subdirectory of the official skalibs tarball, is not provided under the same license.
The license for the skalibs documentation is more restrictive than the license for the source code. Namely:
I am aware that the previous restrictions sound completely ridiculous while the official skalibs documentation is incomplete. As of 2.8.1.0, I'm not going to enforce those restrictions, but if you're going to provide documentation for skalibs, don't keep it to yourself, please send it to me instead. :-)