Docs: Model reference documentation should talk about "why / what is a model"

On the model documentation https://hasura.io/docs/3.0/supergraph-modeling/models shouldn't we mention why we add models?

For example:

Models create a standard API with a, b, c features and compose well with each other. here's an example of a model actually shows up in your API.

And then we go into the reference documentation?

Start with the model documentation page at https://hasura.io/docs/3.0/supergraph-modeling/models and review its existing reference structure. Done means adding a clear explanation of why models are used, describing how they compose and appear in the API, and including a representative example before the reference material.

Written by the indexing model from the issue text.