XEP-0319: API changes

- ``idle`` and ``active`` are now coroutines.

docs/api/plugins/xep_0319.rst

@@ -8,6 +8,30 @@ XEP-0319: Last User Interaction in Presence
     :members:
     :exclude-members: session_bind, plugin_init, plugin_end
 
+Internal API methods
+--------------------
+
+The default API manages an in-memory cache of idle periods.
+
+.. glossary::
+
+    set_idle
+        - **jid**: :class:`~.JID` who has been idling
+        - **node**: unused
+        - **ifrom**: unused
+        - **args**: :class:`datetime`, timestamp of the idle start
+
+        Set the idle start for a JID.
+
+    get_idle
+        - **jid**: :class:`~.JID` to get the idle time of
+        - **node**: unused
+        - **ifrom**: unused
+        - **args**: : unused
+        - **returns**: :class:`datetime`
+
+        Get the idle start timestamp for a JID.
+
 
 Stanza elements
 ---------------