Updated documentation for modmail conversation (#1572)

* Updated documentation for modmail conversation

praw/models/reddit/subreddit.py

@@ -2435,9 +2435,10 @@ def modmail_conversations(
             which to fetch conversations (default: None).
         :param sort: Can be one of: mod, recent, unread, user
             (default: recent).
-        :param state: Can be one of: all, archived, highlighted, inprogress,
-            mod, new, notifications, or appeals, (default: all). "all" does not
-            include internal, archived, or appeals conversations.
+        :param state: Can be one of: all, appeals, archived, default, highlighted,
+            inbox, inprogress, mod, new, notifications (default: all). "all" does not
+            include mod or archived conversations. "inbox" does not include appeals
+            conversations.
 
         Keyword arguments are passed to :func:`.stream_generator`.