[Bug] xPDOQuery->select() incomplete parameter type hint in PHPDoc

[smaddock]

As $columns can be either a CSV or array, this should be either @param mixed $columns, @param array|string $columns or @param string[]|string $columns.

xpdo/src/xPDO/Om/xPDOQuery.php

Line 220 in c4f7bc6

* @param string $columns Columns to return from the query.