The Creating_a_web_service_and_a_web_service_function documentation refers to the web service plugin template from https://github.com/moodlehq/moodle-local_wstemplate. The instructions in that template say:
To test:
1- install the plugin in Moodle
2- Read, setup and run /client/client.php
How you you install the plugin template? In what folder do I extract the template?