Makefile: remove section about packages needed to build Avocado

All the Avocado deps are now either on Fedora or EPEL, so there's no
need for any extra setup, and consequently, for that documentation
section.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

Makefile

-#
-# NOTE: to build Avocado RPM packages extra deps not present out of the box
-# are necessary. These packages are currently hosted at:
-#
-# https://repos-avocadoproject.rhcloud.com/static/avocado-fedora.repo
-# or
-# https://repos-avocadoproject.rhcloud.com/static/avocado-el.repo
-#
-# Since the RPM build steps are based on mock, edit your chroot config
-# file (/etc/mock/<your-config>.cnf) and add the corresponding repo
-# configuration there.
-#
-
 PYTHON=$(shell which python)
 PYTHON_DEVELOP_ARGS=$(shell if ($(PYTHON) setup.py develop --help 2>/dev/null | grep -q '\-\-user'); then echo "--user"; else echo ""; fi)
 VERSION=$(shell $(PYTHON) setup.py --version 2>/dev/null)