Support json schema

[wzy]

Actual Situation

Can copier.yml have a json schema and been published in schemastore?

Desired Situation

Like alacritty:

Proposed solution

This is a reference: cmhughes/latexindent.pl#206

The steps are following:

1. Create a json schema
2. Add its URL to schemastore.

[Jairo Llopis]

Duplicate of #918.