fix: Update the docs of "pause" to state that time will still advance

[Marwes]

This was changed in #2059. This had me extremely confused for some time
as my timeouts fired immediately, without allowing the wrapped future that were
waiting on IO to actually run long enough to finish.

I am not sure about the exact wording here but it should at least say that time is not actually paused. Deprecating "pause" and giving it a more accurate name
may be a good idea as well.

async fn timeout_advances() {
    time::pause();

    timeout(ms(1), async {
        // Change to 1 and the this future resolve, 2 or
        // more and the timeout resolves
        for _ in 0..2 {
            tokio::task::yield_now().await
        }
    })
    .await
    .unwrap();
}

[Darksonn]

grammar nit