Adding section about inflow transactions and EIS interaction

I would like ask for enhancing Narayana documentation for section where information about inflow transactions and interaction with EIS would be part of.

This ask for the addition came from discussion about behaviour of inflow transaction on jbossts mailing list. Particularly information how EIS and TM is expected to interoperate during recovery process. E.g. how EIS is expected to finish transaction when TM jvm crash occurs or how EIS is expected to finish transaction when participant of txn involved under management of TM (TM is manager of subordinate transaction) and such participant independently decides to rollback (after prepare is confirmed) which causes heuristic exception being thrown to EIS RAR and transaction is put to heuristic state.