title: Send Push Notification to Android app upon the data update in the server, and open custom Activity
body: <p>Needed a suggestion/idea.
  I have to send the push notification to the android app when the data is changed/updated in the server.
  I have got a news app, so whenever the news is being updated in the server, the user should get the push notification and when they click the notification, the app should open the link of the news in the app.</p>
  
  <p>What would be the best approach to do so?</p>
  
  <p>I know a bit about FCM, and have played sometime with it, learned about sending the notification from the FCM console, to all the devices using the topic.</p>
  
  <p>Just wondering how can I implement it, rather than using the console, but by just updating the data in the server, and notification should be sent to all the devices which have got the app installed.</p>