Improve the help text for the rdp options
Improve the help text for the rdp options

The previous commit moved rdp options to a central location.
This commit adds additional help text to those options.

Blueprint centralize-config-options-newton

Change-Id: I6d0a474a005794990fb6ac5dba729929977c8343

gooddata/openstack-nova,klmitch/nova,phenoxim/nova,cloudbase/nova,rahulunair/nova,cloudbase/nova,openstack/nova,mahak/nova,vmturbo/nova,hanlind/nova,rahulunair/nova,Juniper/nova,jianghuaw/nova,phenoxim/nova,vmturbo/nova,Juniper/nova,mikalstill/nova,mikalstill/nova,bigswitch/nova,openstack/nova,gooddata/openstack-nova,klmitch/nova,klmitch/nova,hanlind/nova,sebrandon1/nova,gooddata/openstack-nova,hanlind/nova,bigswitch/nova,gooddata/openstack-nova,openstack/nova,sebrandon1/nova,sebrandon1/nova,Juniper/nova,mikalstill/nova,jianghuaw/nova,rajalokan/nova,rajalokan/nova,klmitch/nova,mahak/nova,mahak/nova,jianghuaw/nova,vmturbo/nova,vmturbo/nova,rajalokan/nova,alaski/nova,jianghuaw/nova,alaski/nova,Juniper/nova,rahulunair/nova,rajalokan/nova,cloudbase/nova