Hello!

This is more of a feature request:

In the OpenAPI Overlay Spec there is an "extends" property which can be set on the top level. The spec describes it like this:

"URI reference that identifies the target document (such as an [OpenAPI] document) this overlay applies to."

Could this maybe be supported? Something like this:

openapi-format --overlayFile overlay.yaml -o openapi-updated.yaml

Notice: there is no input file specified since its set in the overlay file

Example Overlay File from Spec docs:

overlay: 1.0.0
info:
  title: Overlay for the Tic Tac Toe API document
  version: 1.0.0
extends: 'https://raw.githubusercontent.com/OAI/learn.openapis.org/refs/heads/main/examples/v3.1/tictactoe.yaml'
...