Update url in HACKING.rst

Change-Id: Id57e35ec7fd058a85953f3154d0be54934fa6e9b
diff --git a/HACKING.rst b/HACKING.rst
index 3a692ff..1a29f1e 100644
--- a/HACKING.rst
+++ b/HACKING.rst
@@ -1,4 +1,4 @@
 tempest-horizon Style Commandments
 ===============================================
 
-Read the OpenStack Style Commandments http://docs.openstack.org/developer/hacking/
+Read the OpenStack Style Commandments https://docs.openstack.org/hacking/latest/