clean up of bk-openstack-basic-install-guide.xml

made copy edit changes
removed The and system before and after OpenStack
removed you and that
changed an to the
changed walks to will walk the user

Change-Id: I8e03a65d3447c219f1b1773d8e8f9861da2882a9
Merge "clean up of bk-openstack-basic-install-guide.xml"