Feature request: Add a flag to `spago init` that excludes comments `package.dhall` and `spago.dhall`

[m-bock]

The comments generated in package.dhall and spago.dhall are very useful for beginners.
A seasoned user may get annoyed by them.

I'd suggest to add a --no-comments flag to spago init

[jhrcek]

I'll tackle this, expect PR soon.