Function signature of `resource_equals` differs from implementation in docs

## How can Bevy's documentation be improved?

In the latest version of bevys docs, the signature of [`resource_equals`](https://docs.rs/bevy/latest/bevy/ecs/schedule/common_conditions/fn.resource_equals.html) seems to be buggy.

I was looking into how the common run conditions were implemented and was a bit confused when I saw this


I needed to check the bevy repos code to verify that the returned closure returns a `bool`.


I don't know how to fix it yet though, but I'll see what I can do!