[FAB-3266] Remove TODO from ledger_interface.go

The following TODO in ledger_interface.go is from
early development, is no longer needed and can be removed:

// TODO detailed illustration of a couple of representations.

Change-Id: I31809b9d28a6da39d28440edb72d5d8faf1b2003
Signed-off-by: Chris Elder <chris.elder@us.ibm.com>

core/ledger/ledger_interface.go

@@ -125,7 +125,6 @@ type TxSimulator interface {
 	//   (at a later time on a different peer) during committing the transactions
 	// Different ledger implementation (or configurations of a single implementation) may want to represent the above two pieces
 	// of information in different way in order to support different data-models or optimize the information representations.
-	// TODO detailed illustration of a couple of representations.
 	GetTxSimulationResults() ([]byte, error)
 }