Update api-ref location

The api documentation is now published on docs.openstack.org instead
of developer.openstack.org. Update all links that are changed to the
new location.

Note that redirects will be set up as well but let's point now to the
new location.

For details, see:
http://lists.openstack.org/pipermail/openstack-discuss/2019-July/007828.html

Change-Id: I4101eced9c4bd26741f760e5651204f5d2dfea0f

doc/source/architecture.rst

@@ -479,4 +479,4 @@ change to a new value:
 
 
 
-.. _Watcher API: https://developer.openstack.org/api-ref/resource-optimization/
+.. _Watcher API: https://docs.openstack.org/api-ref/resource-optimization/

doc/source/index.rst

@@ -83,7 +83,7 @@ API References
 .. toctree::
   :maxdepth: 1
 
-  API Reference <https://developer.openstack.org/api-ref/resource-optimization/>
+  API Reference <https://docs.openstack.org/api-ref/resource-optimization/>
   Watcher API Microversion History </contributor/api_microversion_history>
 
 Plugins

watcher/common/placement_helper.py

@@ -33,7 +33,7 @@ class PlacementHelper(object):
     @staticmethod
     def get_error_msg(resp):
         json_resp = resp.json()
-        # https://developer.openstack.org/api-ref/placement/#errors
+        # https://docs.openstack.org/api-ref/placement/#errors
         if 'errors' in json_resp:
             error_msg = json_resp['errors'][0].get('detail')
         else:

watcher/decision_engine/model/element/volume.py

@@ -22,7 +22,7 @@ from watcher.objects import fields as wfields
 
 
 class VolumeState(enum.Enum):
-    # https://developer.openstack.org/api-ref/block-storage/v3/#volumes-volumes
+    # https://docs.openstack.org/api-ref/block-storage/v3/#volumes-volumes
 
     CREATING = 'creating'
     AVAILABLE = 'available'