add guides to libqi documentation.

Change-Id: I852fed5d5ce98cef5853f87ce387191eb782853a
Reviewed-on: http://gerrit.aldebaran.lan:8080/8239
Reviewed-by: cgestes <gestes@aldebaran-robotics.com>
Tested-by: fmichea <fmichea@aldebaran-robotics.com>