Add stage for illustrating adding Rhea IDs to metabolic conversions

[DeniseSl22]

Add stage for illustrating adding Rhea IDs to metabolic conversions in Advanced Modeling track

[DeniseSl22]

Also check documentation on ChEBI IDs for pH 7.3 : https://www.rhea-db.org/help/chebi-in-rhea#major_microspecies

[DeniseSl22]

Another issue that should be addressed here (in a different step):

What about multi-step reaction, with missing in between reactions, or if several steps are in Rhea as well as a reaction spanning multiple smaller ones?

Current solution:
A->B->C->D ; all individual Rhea IDs, added dotted MIM-conversion from A->D with more general Rhea ID.

[Chris-Evelo]

Sounds like a good solution and one that is extremely useful in the world of elementary path analysis.