Update setting-up-google-firebase-cloud-messaging-server.md

Author: ConnorLand

content/en/docs/refguide/mobile/using-mobile-capabilities/push-notifications/setting-up-google-firebase-cloud-messaging-server.md

@@ -67,7 +67,7 @@ For a native mobile app, your bundle ID will be what you specify for the **App i
 * For iOS, open *ios/Config/config.xcconfig* and consult **BUNDLE_IDENTIFIER** to find your ID
 
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-If you also want to support a custom developer app, repeat above steps and append `.developerapp` to the IDs.
+If you also want to support a [custom developer app](/refguide/mobile/distributing-mobile-apps/building-native-apps/how-to-devapps/), repeat above the steps and append `.developerapp` to the IDs.
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 Click **Deploy**, then **Mobile App**. Your ID is listed as **App Identifier**: