update docs on getting started on lxplus
update docs on getting started on lxplus

rootpy/root_numpy,ndawe/root_numpy,rootpy/root_numpy,scikit-hep/root_numpy,scikit-hep/root_numpy,ndawe/root_numpy,scikit-hep/root_numpy,scikit-hep/root_numpy,ndawe/root_numpy,rootpy/root_numpy,rootpy/root_numpy,ndawe/root_numpy