Update URL for global HACKING document and remove duplicate section

* Related to I579e7c889f3addc2cd40bce0c584bbc70bf435e2

* Remove section on locals since its already in global hacking doc
  (http://git.openstack.org/cgit/openstack-dev/hacking/tree/doc/source/index.rst#n154)

Change-Id: I5acb06dfde6eb7f579d8d52bc31fafbdab8c726d