The method [\ArangoDBClient\Connection::delete](https://github.com/arangodb/arangodb-php/blob/devel/lib/ArangoDBClient/Connection.php#L295) needs an optional body param to [remove multiple documents](https://docs.arangodb.com/3.3/HTTP/Document/WorkingWithDocuments.html#removes-multiple-documents). To avoid a BC break, I recommend to add it as a third optional argument. What do you think?