Subject: guix pull doesn't update the user manual

From: Maxim Cournoyer <[email-masked]>
Date: Fri, 15 Sep 2017 16:39:06 -0400

guix pull should build and install the latest documentation of Guix to
the user profile so that `info guix' always displays the current
documentation.

This seems to confuse Guix users every now and then, myself included,
and the work around of cloning a full copy of the guix sources just to
build the manual is not user friendly nor trivial.