message: Clarify ledger format docs around serialisation of read transactions
diff: @@ -22,6 +22,8 @@ Transaction Format
  The following table describes the structure of a serialised transaction as it is stored in the ledger.
  +.. note:: These serialised transactions in CCF currently describes only the final write set rather than the internal execution path of a transaction; writes are reordered, only the final writes are present, and reads are omitted (read count will be 0).
  +
  +----------+------------------------------------------+-------------------------------------------------------------------------+
  | | Field Type | Description |
  +==========+==========================================+=========================================================================+
  