Cleanup LDAP integration guide
Cleanup LDAP integration guide

This commit fixes a grammar issue in the LDAP integration guide
and it adds prompts to the command-line examples to be more
explicit about where or how commands are being run.

Change-Id: Ic6a5adfbcf2841656929e6c3875889a31d314089

nawawi/openstack,openstack-dev/devstack,dtroyer/devstack,nawawi/openstack,dtroyer/devstack,openstack-dev/devstack