worker-saturation documentation/implementation mismatch

The documentation at https://distributed.dask.org/en/latest/scheduling-state.html claims that the `worker-saturation` default is `inf`. However, this issue (https://github.com/dask/distributed/issues/7213) claims that the default has changed to `1.1`.
Might be useful to match the documentation. I can do this as well, but that will be for somewhere next week probably.

Open the scheduling-state documentation page and read issue #7213 first to confirm the current worker-saturation default. Update the documentation so it matches the implemented default, then verify that the option description consistently states the current value.

Written by the indexing model from the issue text.