message: Variable name mismatch in subscription docs
  In the standalone client example, a variable newMessages holding a query MessageSub is defined but never used; in the body an undefined variable MessageSub is referenced. Renamed to MessageSub uniformly.
diff: @@ -306,7 +306,7 @@ use subscriptions in a Node.js environment.
  ```js
  import { pipe, subscribe } from 'wonka';
  -const newMessages = `
  +const MessageSub = `
  subscription MessageSub {
  newMessages {
  id
  