docs: Upgrading typo fixes

UPGRADING-0.5-to-0.6.md

@@ -36,7 +36,7 @@ The signatures of media uploads, have also changed slightly: rather than expecti
 
 ### Event Handling & sync updaes
 
-If you are using the `client.register_event_handler` function to receive updates on uncoming sync events, you'll find yourself with a deprecation warning now. That is because we've refactored and redsigned the event handler logic to allowing `removing` of event handlers on the fly, too. For that the new `add_event_handler()` (and `add_room_event_handler`) will hand you an `EventHandlerHandle` (pardon the pun), which you can pass to `remove_event_handler`, or by using the convinient `client.event_handler_drop_guard` to create a `DropGuard` that will remove the handler when the guard is dropped. While the code still works, we recommend you switch to the new one, as we will be removing the `register_event_handler` and `register_event_handler_context` in a coming release.
+If you are using the `client.register_event_handler` function to receive updates on incoming sync events, you'll find yourself with a deprecation warning now. That is because we've refactored and redesigned the event handler logic to allowing `removing` of event handlers on the fly, too. For that the new `add_event_handler()` (and `add_room_event_handler`) will hand you an `EventHandlerHandle` (pardon the pun), which you can pass to `remove_event_handler`, or by using the convenient `client.event_handler_drop_guard` to create a `DropGuard` that will remove the handler when the guard is dropped. While the code still works, we recommend you switch to the new one, as we will be removing the `register_event_handler` and `register_event_handler_context` in a coming release.
 
 Secondly, you will find a new [`sync_with_result_callback` sync function][sync with result]. Other than the previous sync functions, this will pass the entire `Result` to your callback, allowing you to handle errors or even raise some yourself to stop the loop. Further more, it will propagate any unhandled errors (it still handles retries as before) to the outer caller, allowing the higher level to decide how to handle that (e.g. in case of a network failure). This result-returning-behavior also punshes through the existing `sync` and `sync_with_callback`-API, allowing you to handle them on a higher level now (rather than the futures just resolving). If you find that warning, just adding a `?` to the `.await` of the call is probably the quickest way to  move forward.