Update docs about notifications

[RayBB]

We should update the docs here:
https://tasks.org/docs/notifications#notifications-are-not-persistent-anymore

I propose this as the new text:

As noted in the release notes of Android 14, persistent/sticky/non-dismissable notifications are no longer supported. As of 13.9 the Tasks app offers a "Swipe to Snooze" in the settings so that notifications come back after being swiped away, you find find this under Settings -> Notifications -> Swipe to snooze.

Also, we should make a note about the default. Is this on by default? Imo it probably should be since that's what the behavior was before, however when I updated the app it wasn't enabled by default.