Improved config validation error message

Author: glye

src/bundle/Core/DependencyInjection/Configuration/Parser/PasswordHash.php

@@ -51,7 +51,7 @@ public function addSemanticConfig(NodeBuilder $nodeBuilder): void
 
                                 return !in_array($hashType, User::SUPPORTED_PASSWORD_HASHES, true);
                             })
-                            ->thenInvalid('Invalid password hash type "%s".')
+                            ->thenInvalid('Invalid password hash type "%s". If you tried to use Argon2, make sure it\'s compiled in PHP.')
                         ->end()
                     ->end()
                     ->booleanNode('update_type_on_change')