Deprecating a field in the Schema

Sometimes it can be helpful to deprecate a field in the Schema without removing it altogether. This snippet shows how to deprecate the `Post.excerpt` field. You can use this technique to deprecate other fields. After using this snippet, we can verify in the WPGraphQL Schema Docs that the field is indeed deprecated:

Register a basic Mutation

This snippet shows how to register a basic GraphQL Mutation with a single input field, a single output field, and the input is simply returned as the value for the output.