Update guide.mdx (#18694)

Author: freetonik

src/content/docs/workflows/get-started/guide.mdx

@@ -62,7 +62,7 @@ type Params = {
 export class MyWorkflow extends WorkflowEntrypoint<Env, Params> {
 	async run(event: WorkflowEvent<Params>, step: WorkflowStep) {
 		// Can access bindings on `this.env`
-		// Can access params on `event.params`
+		// Can access params on `event.payload`
 
 		const files = await step.do('my first step', async () => {
 			// Fetch a list of files from $SOME_SERVICE