ValidateCommand: add a comment that we didn't forget $lockErrors

src/Composer/Command/ValidateCommand.php

@@ -140,6 +140,7 @@ EOT
             $doPrintSchemaUrl = $printSchemaUrl;
         } else {
             $io->write('<info>' . $name . ' is valid</info>');
+            // if ($lockErrors) then they will be displayed below
         }
 
         if ($doPrintSchemaUrl) {