feat: add deprecation label to redoc-cli

[AlexVarchuk]

What/Why/How?

We deprecate redoc-cli and move our focus to Redoc. Instead of redoc-cli you can use @redocly/cli.

redoc-cli serve <spec> -> @redocly/cli preview-docs <spec>
redoc-cli bundle/build <spec> -> @redocly/cli build-docs <spec>

Reference

Testing

Screenshots (optional)

Check yourself

• [x] Code is linted
• [x] Tested
• [ ] All new/updated code is covered with tests