Some more invalid PHPDocs in legacy classes

Signed-off-by: Lukas Reschke <lukas@statuscode.ch>

Author: LukasReschke

lib/private/legacy/db.php

@@ -105,7 +105,7 @@ static public function isManipulation( $sql ) {
 	 * @param mixed $stmt OC_DB_StatementWrapper,
 	 *					  an array with 'sql' and optionally 'limit' and 'offset' keys
 	 *					.. or a simple sql query string
-	 * @param array $parameters
+	 * @param array|null $parameters
 	 * @return OC_DB_StatementWrapper
 	 * @throws \OC\DatabaseException
 	 */