"Namespaces" sample code in README won't work

In the last line of [the sample code of namespaces in README](https://github.com/goto100/xpath/blob/20ce534af81096b1c02cbdeb676ad58231a52ed7/README.md), `TypeError: Cannot read property 'namespaceURI' of undefined` is thrown because `xpath.select(...)` returns an empty array.

Replacing `"myns/"` with `"myns" in the XPath, it works as expected.