[DX] Clarify the possibilities of ListSignal operation types

[taefi]

The listing of the runtime types for signal operations can be clarified further, especially the possibilities for the operations in ListSignal. The current documentation lists insertLast and remove as the ListSignal API, and further down in the documentation, where it is listing the possible runtime operation types, it expects the reader to deduct that, though, SetValueOperation and ReplaceValueOperation are happening to the internal ValueSignal entries of a ListSignal, the operation validator should also cover them as well when defining rejection/allowance rules.