Clarify that python-dbus is only installed in the -build variants of balenaOS #1505
Description
The Network Setup page says: "If you are using our Python base images, then you do not have to install the dbus module, since it is already included there." This is not correct; we currently install this only in the -build variants of the Python balenaOS image.
The same mistake is made here, where we say "Note: pip, python-dbus, virtualenv, setuptools are preinstalled in all python images."