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: I1d794ae8c3058b3e2c1ffd27fde4ddbe69edd5f7
diff --git a/ironic_tempest_plugin/tests/scenario/baremetal_standalone_manager.py b/ironic_tempest_plugin/tests/scenario/baremetal_standalone_manager.py
index 94780a8..4cf500d 100644
--- a/ironic_tempest_plugin/tests/scenario/baremetal_standalone_manager.py
+++ b/ironic_tempest_plugin/tests/scenario/baremetal_standalone_manager.py
@@ -101,7 +101,7 @@
 
         For a full list of available parameters, please refer to the official
         API reference:
-        http://developer.openstack.org/api-ref/networking/v2/index.html#create-port
+        https://docs.openstack.org/api-ref/network/v2/index.html#create-port
 
         :returns: server response body.
         """