Add Plugin.upgrade to documentation

Signed-off-by: Joffrey F <joffrey@docker.com>
2017-02-23 18:15:40 -08:00 · 2017-02-23 18:15:40 -08:00 · 5268a31116
--- a/docs/plugins.rst
+++ b/docs/plugins.rst
@ -35,3 +35,4 @@ Plugin objects
  .. automethod:: reload
  .. automethod:: push
  .. automethod:: remove
+  .. automethod:: upgrade