docs(examples): Avoid a warning from zapier cli when using the custom…

…-auth sample (#724)

* Avoid a warning from zapier cli when using the sample

example-apps/custom-auth/authentication.js

@@ -47,7 +47,7 @@ module.exports = {
 
     // Define any input app's auth requires here. The user will be prompted to enter
     // this info when they connect their account.
-    fields: [{ key: 'apiKey', label: 'API Key', required: true }],
+    fields: [{ key: 'apiKey', label: 'API Key', required: true, helpText: 'Find the API Key in your [app settings page](https://yourapp.com/settings)' }],
 
     // The test method allows Zapier to verify that the credentials a user provides
     // are valid. We'll execute this method whenever a user connects their account for