Eligibility of CC-BY-SA for documentation within a software project

[Anton S. Lytvynenko]

Dear users and admins,

I would like to transfer the mercurial repository with our project to
Savannah. The code itself is licensed under GPL3+ and the user manual is
under CC-BY-SA. However, I am a bit confused by the guidelines and FAQs
regarding the documentation licenses on the GNU site and on the Savannah
one: as I've understood, FDL is recommended, while the ND and NC flavors
of the Creative Commons ones are considered non-free. CC-BY-SA is
considered eligible for artworks, but it is not clear if it is
acceptable for the software documentation.

I've tried to search the mailing list archives but failed to find the
answer. Could you please clarify this question?

Yours sincerely,

Anton Lytvynenko