Add links to capabilities

[m-mohr]

The API recommends to add links to capabilities so that (also non-openEO) clients can better discover the service:

Links related to this service, e.g. the homepage of the service provider or the terms of service.
It is highly RECOMMENDED to provide links with the following rel (relation) types:

1. version-history: A link back to the Well-Known URL (see /.well-known/openeo) to allow clients to work on the most recent version.
2. terms-of-service: A link to the terms of service. If a back-end provides a link to the terms of service, the clients MUST provide a way to read the terms of service and only connect to the back-end after the user agreed to them. The user interface MUST be designed in a way that the terms of service are not agreed to by default, i.e. the user MUST explicitly agree to them.
3. privacy-policy: A link to the privacy policy (GDPR). If a back-end provides a link to a privacy policy, the clients MUST provide a way to read the privacy policy and only connect to the back-end after the user agreed to them. The user interface MUST be designed in a way that the privacy policy is not agreed to by default, i.e. the user MUST explicitly agree to them.
4. service-desc or service-doc: A link to the API definition. Use service-desc for machine-readable API definition and service-doc for human-readable API definition. Required if full OGC API compatibility is desired.
5. conformance: A link to the Conformance declaration (see /conformance). Required if full OGC API compatibility is desired.
6. data: A link to the collections (see /collections). Required if full OGC API compatibility is desired.

It would be great if you could implement those links, if applicable to your service. I'm especially interested in 1, 2, 3, and 6.