Simplewallet.cpp: Add export_outputs help

See #6547

src/simplewallet/simplewallet.cpp

@@ -5937,7 +5937,7 @@ bool simple_wallet::show_balance_unlocked(bool detailed)
   if (m_wallet->has_multisig_partial_key_images())
     extra = tr(" (Some owned outputs have partial key images - import_multisig_info needed)");
   else if (m_wallet->has_unknown_key_images())
-    extra += tr(" (Some owned outputs have missing key images - import_key_images needed)");
+    extra += tr(" (Some owned outputs have missing key images - export_outputs, import_outputs, export_key_images, and import_key_images needed)");
   success_msg_writer() << tr("Currently selected account: [") << m_current_subaddress_account << tr("] ") << m_wallet->get_subaddress_label({m_current_subaddress_account, 0});
   const std::string tag = m_wallet->get_account_tags().second[m_current_subaddress_account];
   success_msg_writer() << tr("Tag: ") << (tag.empty() ? std::string{tr("(No tag assigned)")} : tag);