Add Diagrams to Concepts & CRDs section of the Package Managment Section

The docs at [Concepts and CRDs](https://carvel.dev/kapp-controller/docs/v0.48.x/packaging/) contain a lot of details and it is hard to grasp how the CRDs are related to each other. Enhance the docs on this page by adding a diagram that summarizes the relationship between the various CRDs with annotations on the diagram to provide context. Such a diagram can make the concepts much easier to understand for a new user.

Start with the linked Concepts and CRDs page in the Package Management documentation and identify the CRDs and relationships it describes. Add a diagram with annotations that summarizes those relationships, then verify that the diagram makes the concepts understandable without changing the documented behavior.

Written by the indexing model from the issue text.