Expand tutorials with HFC era transitions

The current consensus tutorials do not cover transitioning into different eras. This is a crucial part of Consensus, and such a tutorial would greatly help us understand it. Therefore, to disseminate the knowledge among the team thereby increasing the bus-factor, we should expand the tutorials to cover this aspect.

Another option or addition to this would be to develop a HFC from scratch. This however might take a considerable time, so we could either sketch such an implementation in the context of this ticket, or create a new one.

Note that we already have tests that transition from one era to another (`AtoB`). We could expand on the instances defined on these tests.