Add explanation on how to install maven on Ubuntu :)
Add explanation on how to install maven on Ubuntu :)

Change-Id: I6034d047794333467034d4480cd4f0983ccbb0a4

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