It seems PhoneGap generates that file automatically when config.xml is modified.
I wish to add Ad network\'s activities, services, etc in AndroidM
You probably want to check out cordova-custom-config.
It supports many extra settings in the cordova config.xml to customise the AndroidManifest.xml.
I'm using it to change the android:configChanges setting (adding uiMode to stop it from reloading when docking/undocking) and it works great.
The cordova-custom-config github page shows a full example with all supported options so it's very easy to setup.