message: fix response attributes for get_account_state API
  Closes:
  Approved by: fallentree
diff: @@ -633,11 +633,11 @@ A Libra account.
  </td>
  </tr>
  <tr>
  - <td>balance
  + <td>balances
  </td>
  - <td><a href="#amount---type">Amount</a>
  + <td><a href="#amount---type">Array of Amount objects </a>
  </td>
  - <td>Balance of given account
  + <td>Balances of all the currencies associated with an account
  </td>
  </tr>
  <tr>
  