[docs] Fix typos

docs/api.rst

@@ -3215,7 +3215,7 @@ AuditLogDiff
 
     .. attribute:: invitable
 
-        Whetheer non-moderators can add users to this private thread.
+        Whether non-moderators can add users to this private thread.
 
         :type: :class:`bool`
 

docs/intro.rst

@@ -106,7 +106,7 @@ A quick example to showcase how events work:
             print(f'Logged on as {self.user}!')
 
         async def on_message(self, message):
-            print(f'Message from {messsage.author}: {message.content}')
+            print(f'Message from {message.author}: {message.content}')
 
     client = MyClient()
     client.run('my token goes here')

docs/migrating.rst

@@ -1029,7 +1029,7 @@ The following have been removed:
 
     - Consider using the newer documented :func:`on_socket_event_type` event instead.
 
-Miscellanous Changes
+Miscellaneous Changes
 ----------------------
 
 The following changes have been made: