update docstrings about the new pin messages permission

Author: Snipy7374

disnake/message.py

@@ -2180,7 +2180,7 @@ async def unpin(self, *, reason: Optional[str] = None) -> None:
 
         Unpins the message.
 
-        You must have the :attr:`~Permissions.manage_messages` permission to do
+        You must have the :attr:`~Permissions.pin_messages` permission to do
         this in a non-private channel context.
 
         Parameters

disnake/permissions.py

@@ -760,7 +760,7 @@ def send_tts_messages(self) -> int:
 
     @flag_value
     def manage_messages(self) -> int:
-        """:class:`bool`: Returns ``True`` if a user can delete or pin messages in a text channel.
+        """:class:`bool`: Returns ``True`` if a user can delete messages in a text channel.
 
         .. note::