[very small] ensure lightdash generate keeps yaml copyright notice

Description

lightdash generate is very useful to generate information on fields we want to show on lightdash, saving the developer from writing lots of lines of code. One pain for myself is that this function removes any copyright information in the first line.

Example .yml

# Company Name, Inc. Proprietary and Confidential. Copyright 2022.

version: 2
models:
  - name: test
    columns:
      - name: id
        description: ""
        meta:
          dimension:
            type: string

When running lightdash generate this removes line 1, the copyright comment. This means that the .yml will fail our linting process.

What problem does this solve?

Described above

[TuringLovesDeathMetal]

That’s annoying 😓 added to the backlog - hopefully should be an easy fix 🤞

[olly-writes-code]

thanks for the quick turnaround on this one!