Clarify and fix some docstrings

telethon/client/buttons.py

@@ -47,7 +47,8 @@ class ButtonMethods(UpdateMethods):
 
                         self.add_event_handler(
                             button.callback,
-                            events.CallbackQuery(data=button.data)
+                            events.CallbackQuery(data=getattr(
+                                button.button, 'data', None))
                         )
 
                     button = button.button

telethon/client/dialogs.py

@@ -162,9 +162,9 @@ class DialogMethods(UserMethods):
             *, timeout=None, total_timeout=60, max_messages=100,
             replies_are_responses=True):
         """
-        Returns an iterator over the dialogs, yielding 'limit' at most.
-        Dialogs are the open "chats" or conversations with other people,
-        groups you have joined, or channels you are subscribed to.
+        Creates a `Conversation <telethon.tl.custom.conversation.Conversation>`
+        with the given entity so you can easily send messages and await for
+        responses or other reactions. Refer to its documentation for more.
 
         Args:
             entity (`entity`):