Starwars Mutation example

[kevleyski]

Many of the example here work

https://graphql.org/learn/queries/

But

mutation CreateReviewForEpisode($ep: Episode!, $review: ReviewInput!) {
createReview(episode: $ep, review: $review) {
stars
commentary
}
}

results in

"errors": [
{
"message": "Schema is not configured for mutations.",

Would be great if there was an example mutation (in my case I'm using warp) an end-to-end query/mutation/sub example that includes a working mutable data context would help many for sure