Missing PROTOCOL_PATH setting

[gilesknap]

https://epics-containers.github.io/main/tutorials/generic_ioc.html#example-ioc-instance
is missing the PROTOCOL PATH setting required for it to run

As discussed here:
infn-epics/infn-epics-ioc#3
infn-epics/infn-epics-ioc#3 (comment)

[gilesknap]

This section should be updated to use the template from services/.ioc-template. The config.yaml in that already includes the PROTOCOL path.

Also the Ansible ioc role already generates the schema for you at /epics/ibek-defs/ioc.schema.json and that is included in the above template.

Update text to explain the schema generation by Ansible instead of suggesting calling ibek to do it.