[Feedback] port custom subscription for GraphQL transformer v1 to new transformer docs

[josefaidt]

Page: /cli-legacy/graphql-transformer/examples

Feedback:

[josefaidt]

found this doc in the guides section https://docs.amplify.aws/guides/api-graphql/subscriptions-by-id/q/platform/js/

[renebrandel]

Closing this issue because it's handled by-default with the server-side subscription filtering experience. https://docs.amplify.aws/cli/graphql/data-modeling/#server-side-filtering-for-subscriptions