Define plan for `service::telemetry` configuration section evolution

[mx-psi]

We intend to use the configuration schema defined by the OpenTelemetry Configuration WG to be used under the service::telemetry section. This schema may not be ready or stable when we intend to release the Collector v1 distro. To prepare for this, we need to decide how we are going to handle the transition. Do we want to support the old and the new configuration schema? Do we want to adopt the Configuration WG one and do some backwards-compatible shim if any breaking changes occur?

[iblancasa]

@mx-psi can you link to the OpenTelemetry Configuration WG schema?

[codeboten]

Here's the repo for the schema https://github.com/open-telemetry/opentelemetry-configuration