Doc: https://smartcontracts.org/docs/language-guide/actor-classes.html doesn't mention cycle provisioning of created actors on the IC

[crusso]

... probably because they aren't supported in the online interpreter. We should add least comment on this, or fix the interpreter to have notional cycles.

The example in the repo does address this:
https://github.com/dfinity/examples/blob/faa33cca9f2a96207894ab77183be64f1db0b290/motoko/classes/src/map/Map.mo#L31