[tox] Install "pyramid" dependencies in "doc" environment
Otherwise most of the cubicweb.pyramid API doc fails to build. For this we
skip installation in the "doc" environment and source the new
requirements/doc.txt which will install cubicweb[pyramid], thus pulling
cubicweb plus pyramid's dependencies.
Furthermore this requirements/doc.txt would be useful to build to
documentation on readthedocs.
etc/init.d
etc/cubicweb.d
etc/bash_completion.d
usr/bin
usr/share/doc/cubicweb-ctl
var/log/cubicweb
var/lib/cubicweb/backup
var/lib/cubicweb/instances