Example of a primitive in tutorial is outdated

[DigitalBrains1]

We have this example. But at a glance there are several things wrong:

1. It matches on (Clock _) which does not type-check (we have a second argument these days).
2. It uses NOINLINE. I don't think we should use CLASH_OPAQUE either; I think we should point out people should probably use a relatively recent GHC and OPAQUE for their own primitives. And perhaps point out that if they choose an old GHC nonetheless, they should use NOINLINE.
3. We enhanced that specific primitive in a number of ways. We should decide whether we simplify the real code, present the real code or present a different primitive altogether to keep the discussion focussed. One of the enhancements that stands out to me is that we reduced the number of formal arguments to improve simulation performance. We also improved handling of XExceptions a lot.

Point 2 will apply to more documentation, by the way.