Merge "Add releasenote for 'subnet list' command support"

Author: Jenkins

releasenotes/notes/add-subnet-list-command-970f4b397469bdc6.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Add support for the ``subnet list`` command.
+    [Bug `1523258 <https://bugs.launchpad.net/python-openstackclient/+bug/1523258>`_]