Clarify pip install section
Clarify pip install section

The section contained links to python-novaclient in the pip install
section and mixed setup of clients and pypi. This patch completly
reworks the content and updates information for openSUSE and SLES.

Change-Id: I00dcb3203530dc7a52e2ae1368a52991f89b4908

AlekhyaMallina-Vedams/openstack-manuals,saeki-masaki/openstack-manuals,kairoaraujo/openstack-manuals,Akasurde/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,kairoaraujo/openstack-manuals,Akasurde/openstack-manuals,gongysh2004/openstack-manual,AlekhyaMallina-Vedams/openstack-manuals,potsmaster/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,saeki-masaki/openstack-manuals,potsmaster/openstack-manuals,gongysh2004/openstack-manual