message: [doc] fix first transaction doc bug.
diff: @@ -29,7 +29,7 @@ After connecting to the node, let's first create two accounts. Here we assume th
  Let's do it!.
  ``` bash
  -starcoin% dev get_coin -v 5000000
  +starcoin% dev get_coin -v 100000000000
  +-----------------+------------------------------------------------------------------+
  | gas_unit_price | 1 |
  +-----------------+------------------------------------------------------------------+
  @@ -59,7 +59,7 @@ starcoin% account show 1d8133a0c1a07366de459fb08d28d2a6
  +--------------------+------------------------------------------------------------------+
  | auth_key_prefix | 7bc6066656bb248755686d2ab78aef14 |
  +--------------------+------------------------------------------------------------------+
  -| balances.STC | 5000000 |
  +| balances.STC | 100000000000 |
  +--------------------+------------------------------------------------------------------+
  | sequence_number | 0 |
  +--------------------+------------------------------------------------------------------+
  