Add release note for "ip floating delete/list" commands for neutron network

Change-Id: Ic90abf106a06edf9af4fe4c8938ab92bfdd8bb42
partial-Bug: 1519502
Related-to: blueprint neutron-client

Author: Tang Chen

releasenotes/notes/bug-1519502-f72236598d14d350.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - Command ``ip floating delete`` is now available for neutron network.
+    [Bug `1519502 <https://bugs.launchpad.net/python-openstackclient/+bug/1519502>`_]
+  - Command ``ip floating list`` is now available for neutron network.
+    [Bug `1519502 <https://bugs.launchpad.net/python-openstackclient/+bug/1519502>`_]