Add missing auth0-variables example from tutorial 05 (#116)

Author: kjkurtz

05-Token-Renewal/src/Auth/auth0-variables.js.example

@@ -0,0 +1,5 @@
+export const AUTH_CONFIG = {
+  domain: '{DOMAIN}',
+  clientId: '{CLIENT_ID}',
+  callbackUrl: 'http://localhost:3000/callback'
+}