Update HACKING.rst per recent changes
Update HACKING.rst per recent changes

Added "is not" usage with examples
Fixed "not in" usage description
* https://review.openstack.org/#/c/20877/

Change-Id: I89fbc62a8b31bc7ef750cc1e80f73b9c1e366fd3

ntt-sic/glance,paramite/glance,klmitch/glance,JioCloud/glance,saeki-masaki/glance,ozamiatin/glance,kfwang/Glance-OVA-OVF,openstack/glance,dims/glance,vuntz/glance,scripnichenko/glance,citrix-openstack-build/glance,kfwang/Glance-OVA-OVF,citrix-openstack-build/glance,stevelle/glance,JioCloud/glance,SUSE-Cloud/glance,vuntz/glance,redhat-openstack/glance,ntt-sic/glance,takeshineshiro/glance,akash1808/glance,tanglei528/glance,akash1808/glance,darren-wang/gl,saeki-masaki/glance,takeshineshiro/glance,scripnichenko/glance,SUSE-Cloud/glance,cloudbau/glance,cloudbau/glance,dims/glance,jumpstarter-io/glance,tanglei528/glance,openstack/glance,stevelle/glance,wkoathp/glance,klmitch/glance,ozamiatin/glance,sigmavirus24/glance,rajalokan/glance,rickerc/glance_audit,openstack/glance,jumpstarter-io/glance,rickerc/glance_audit,rajalokan/glance,redhat-openstack/glance,darren-wang/gl,wkoathp/glance,paramite/glance,sigmavirus24/glance