Fix errors in hot_spec doc
Fix errors in hot_spec doc

allowed_values is not written properly in an example, and fix a
sentence.

Change-Id: I6544033365b937e1e0fc33d23c143d6a3291273b

dragorosson/heat,gonzolino/heat,dragorosson/heat,pshchelo/heat,cryptickp/heat,cwolferh/heat-scratch,openstack/heat,noironetworks/heat,dims/heat,jasondunsmore/heat,srznew/heat,jasondunsmore/heat,maestro-hybrid-cloud/heat,pshchelo/heat,noironetworks/heat,rdo-management/heat,redhat-openstack/heat,takeshineshiro/heat,srznew/heat,cwolferh/heat-scratch,pratikmallya/heat,NeCTAR-RC/heat,steveb/heat,maestro-hybrid-cloud/heat,dims/heat,takeshineshiro/heat,redhat-openstack/heat,gonzolino/heat,rh-s/heat,miguelgrinberg/heat,pratikmallya/heat,steveb/heat,miguelgrinberg/heat,cryptickp/heat,NeCTAR-RC/heat,openstack/heat,rdo-management/heat,rh-s/heat