simplewallet: add pending/pool/failed in the show_transfers help

reported by nioc

src/simplewallet/simplewallet.cpp

@@ -678,7 +678,7 @@ simple_wallet::simple_wallet()
   m_cmd_binder.set_handler("rescan_spent", boost::bind(&simple_wallet::rescan_spent, this, _1), tr("Rescan blockchain for spent outputs"));
   m_cmd_binder.set_handler("get_tx_key", boost::bind(&simple_wallet::get_tx_key, this, _1), tr("Get transaction key (r) for a given <txid>"));
   m_cmd_binder.set_handler("check_tx_key", boost::bind(&simple_wallet::check_tx_key, this, _1), tr("Check amount going to <address> in <txid>"));
-  m_cmd_binder.set_handler("show_transfers", boost::bind(&simple_wallet::show_transfers, this, _1), tr("show_transfers [in|out] [<min_height> [<max_height>]] - Show incoming/outgoing transfers within an optional height range"));
+  m_cmd_binder.set_handler("show_transfers", boost::bind(&simple_wallet::show_transfers, this, _1), tr("show_transfers [in|out|pending|failed|pool] [<min_height> [<max_height>]] - Show incoming/outgoing transfers within an optional height range"));
   m_cmd_binder.set_handler("rescan_bc", boost::bind(&simple_wallet::rescan_blockchain, this, _1), tr("Rescan blockchain from scratch"));
   m_cmd_binder.set_handler("set_tx_note", boost::bind(&simple_wallet::set_tx_note, this, _1), tr("Set an arbitrary string note for a txid"));
   m_cmd_binder.set_handler("get_tx_note", boost::bind(&simple_wallet::get_tx_note, this, _1), tr("Get a string note for a txid"));