Add a hint about activation of CDK1, that it can appear from nothing ->CDK1 and disappear as well CDK1->

[A2P2]

• Messages from the chat:
• A small hint: for this type of modelling, molecules can also appear from nothing or dissappear into nothing. For example: R1: -> P; k1; is a viable reaction.
• That's helpful, thank you. Could we have inferred this from the introduction or is this just something you kind of "have to know"?
• There is no clear hint for it in the Notebook. You might have known it, but it depends on your background. We will add it as a hint for the next year. Important: understand that this is just an abstraction for modelling, in the real biological system of course CDK1 comes from inactive CDK1, which in turn comes from protein synthesis.