General updates to the dashboard chapter
General updates to the dashboard chapter

As per the bug, updated the wording for the Dashboard chapter.
Watch this space for the rest of the book.

Change-Id: Idc68e3f241392cae48b7e786951222984c337e09
Partial-Bug: #1251195

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