Update README.md

Author: AbdullahDiaa

README.md

@@ -16,7 +16,8 @@ cordova plugin add pushbots-cordova-plugin --save
 ## Usage
 
 1. Intialize Pushbots in deviceReady section:
-Firebase credentials: https://www.pushbots.help/en/articles/498201-the-google-part-firebase-credentials
+
+**Firebase credentials:** https://www.pushbots.help/en/articles/498201-the-google-part-firebase-credentials
 
 ```javascript
 window.plugins.PushbotsPlugin.initialize("PUSHBOTS_APP_ID", {"android":{"sender_id":"SENDER_ID", "fcm_app_id":"FCM_APP_ID", "web_api_key":"WEB_API_KEY", "project_id":"PROJECT_ID"});