Small changes in doc

Signed-off-by: chandr-andr (Kiselev Aleksandr) <chandr@chandr.net>

Author: chandr-andr

docs/components/listener.md

@@ -121,7 +121,7 @@ async def main() -> None:
 - `channel`: name of the channel to listen.
 - `callback`: coroutine callback.
 
-Add new callback to the channel, can be called more than 1 times.
+Add new callback to the channel, can be called multiple times (before or after `listen`).
 
 Callback signature is like this:
 ```python