Clarify how to use services list in addon's config.yaml

[baflo]

From the documentation for the addon configuration it's unclear how to use the services option and what it is for, actually. At first I thought it can be used to configure the addon to provide integration services (such as backup.create), but after a while of researching I rather think it provides services like mysql and mqtt.

It that is true, how does services: ["mqtt:provide"] differ from discovery: ["mqtt"]?

developers.home-assistant/docs/add-ons/configuration.md

Line 176 in e86f148

| `services` | list | | A list of services that will be provided or consumed with this add-on. Format is `service`:`function` and functions are: `provide` (this add-on can provide this service), `want` (this add-on can use this service) or `need` (this add-on needs this service to work correctly).