Change default configuration from XML to YAML

[predic8]

We are wondering if we should make YAML the default configuration for Membrane. What do you think?

[predic8]

May be we can link to the schema in the apis.yaml files

# yaml-language-server: $schema=https://example.org/myresource.schema.json
apiVersion: example.org/v1
kind: MyResource
spec:
  image: nginx
  replicas: 3