Different worker.js examples

[DawsonCTO]

I've been implementing the Cloudflare worker for Prerender integration. It seems the documentation points me to two different implementations of with worker.js. The example on the master branch uses an API_KEY variable where the Prerender token is to be assigned and another example from Prerender documentation uses an environment variable PRERENDER_TOKEN that is assigned via the Cloudflare add variable UI.

Is the worker.js example on master the correct implementation to use?