Missing yang file on hello world example

version: Oxygen
page: developer-guide/developing-apps-on-the-opendaylight-controller

There seems to be an error with the tutorial, in the second step of the Add a Simple Hello World RPC API, there is no file to use as reference. The instruction seems to imply that there should be a file following the line.

Edit this file as follows. In the following example, we are adding the code in a YANG module to define the hello-world RPC: