Update quickbooks.php (#1365)

- Alter message in case test isn't accurate
- Fix link to QBO settings
- Fix string domain

public_html/wp-content/mu-plugins/quickbooks/quickbooks.php

@@ -30,7 +30,7 @@ function check_qbo_connection() {
 	$client  = get_client();
 
 	if ( ! $client->has_valid_token() && function_exists( 'slack_dm' ) ) {
-		slack_dm( 'QBO token invalid. Visit <https://wordcamp.org/wp-admin/network/settings.php> to check connection.', 'dotorg' );
+		slack_dm( 'QBO token may be invalid. Visit <https://wordcamp.org/wp-admin/network/settings.php?page=quickbooks> to check connection.', 'wordcamp' );
 	}
 }