Eliminate duplicate JSON Schema, link to the one in OCM Repo

[In-Ko]

Description
There are currently two JSON Schema for the Component Descriptor, one in this repo (OCM-SPEC) and one in Repo "OCM". We should not have two schemas, but only one.
We decided to keep the one in the OCM-Repo, as it is required there also for technical reasons (due to the library and CLI being also in that Repo), and get rid of the JSON schema in the OCM-SPEC repo.

1. Delete this: https://github.com/open-component-model/ocm-spec/tree/main/doc/specification/formats/compdesc (and if required link to the ones mentioned under (2), for people who have this URL bookmarked already)
2. Keep this and use it for now as the one-and-only JSON Schema place: https://github.com/open-component-model/ocm/tree/main/docs/formats/compdesc

[jensh007]

accidentally closed.

[jensh007]

#57 added