XEP-0054: API changes

- ``get_vcard``, ``publish_vcard`` are now coroutines.

docs/api/plugins/xep_0054.rst

@@ -8,6 +8,38 @@ XEP-0054: vcard-temp
     :members:
     :exclude-members: session_bind, plugin_init, plugin_end
 
+Internal API methods
+--------------------
+
+This plugin maintains by default an in-memory cache of the received
+VCards.
+
+.. glossary::
+
+    set_vcard
+        - **jid**: :class:`~.JID` of whom to set the vcard
+        - **node**: unused
+        - **ifrom**: unused
+        - **args**: :class:`~.VCardTemp` object to store for this JID.
+
+        Set a VCard for a JID.
+
+    get_vcard
+        - **jid**: :class:`~.JID` of whom to set the vcard
+        - **node**: unused
+        - **ifrom**: :class:`~.JID` the request is coming from
+        - **args**: unused
+        - **returns**: :class:`~.VCardTemp` object for this JID or None.
+
+        Get a stored VCard for a JID.
+
+    del_vcard
+        - **jid**: :class:`~.JID` of whom to set the vcard
+        - **node**: unused
+        - **ifrom**: unused
+        - **args**: unused
+
+        Delete a stored VCard for a JID.
 
 Stanza elements
 ---------------