docs: clean up redundant information about installing packages

The previous text "please adapt to your platform" is enough.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

docs/source/GetStartedGuide.rst

@@ -68,8 +68,6 @@ Note that `python` and `pip` should point to the Python interpreter version 2.7.
 If you're having trouble to install, you can try again and use the command line
 utilities `python2.7` and `pip2.7`.
 
-For Debian users, use `apt-get` to install the proper dependencies that `yum` installs.
-
 Using Avocado
 =============