Feature: Generate docs.md files with link to schema.yml columns

[awoehrl]

Is your feature request related to a problem? Please describe. dbt has the option to define column descriptions in markdown files. It would be great to have an option in dbt-coves to generate schema descriptions in the style of:

      - name: status
        description: '{{ doc("orders_status") }}'

And generate a docs.md file that has the columns defined, so I would just need to add my descriptions there.