[Go] Add example with input (#236)

go/samples/coffee-shop/main.go

@@ -19,9 +19,14 @@
 //
 // go run . &
 //
-// Tell it to run an action:
+// Tell it to run an action. Here are some examples:
+//
+// Flow without input:
 //
 // curl -d '{"key":"/flow/testAllCoffeeFlows/testAllCoffeeFlows", "input":{"start": {"input":null}}}' http://localhost:3100/api/runAction
+// Flow with input:
+//
+// curl -d '{"key":"/flow/simpleGreeting/simpleGreeting", "input":{"start": {"input":{"customerName": "John Doe"}}}}' http://localhost:3100/api/runAction
 //
 // In production mode (GENKIT_ENV missing or set to "prod"):
 // Start the server listening on port 3400: