Make clean removes:
doc/contributing.fr.texi
doc/guix.fr.texi

We had a discussion on #guix with roptat, and a few others.
I have found out, that after removing $(TRANSLATED_INFO)
from $(BUILT_SOURCES) in doc/local.mk these files are not
deleted any more. I have doubts that this is a correct fix, as
this might break dependency resolution.

I also noticed, that after running make these two files end up with
different content.

If you think this fix is ok, I will send a patch.