chore(firebase-core): README update (#184)

* chore(firebase-core): README update

* chore: update

Author: Ombuweb

packages/firebase-core/README.md

@@ -1,25 +1,60 @@
 # @nativescript/firebase-core
 
+A plugin to initialize [FirebaseApp](https://firebase.google.com/docs/reference/android/com/google/firebase/FirebaseApp) in your app.
+It should be used with any of:
+
+- [@nativescript/firebase-admob](../firebase-admob/)
+- [@nativescript/firebase-analytics](../firebase-admob/)
+- [@nativescript/firebase-app-check](../firebase-app-check/)
+- [@nativescript/firebase-app-check-debug](../firebase-app-check-debug/)
+- [@nativescript/firebase-auth](../firebase-auth/)
+- [@nativescript/firebase-crashlytics](../firebase-analytics/)
+- [@nativescript/firebase-database](../firebase-database/)
+- [@nativescript/firebase-dynamic-links](../firebase-dynamic-links/)
+- [@nativescript/firebase-firestore](../firebase-firestore/)
+- [@nativescript/firebase-functions](../firebase-functions/)
+- [@nativescript/firebase-in-app-messaging](../firebase-in-app-messaging/)
+- [@nativescript/firebase-installations](../firebase-installations/)
+- [@nativescript/firebase-messaging](../firebase-messaging/)
+- [@nativescript/firebase-messaging-core](../firebase-messaging-core/)
+- [@nativescript/firebase-performance](../firebase-performance/)
+- [@nativescript/firebase-remote-config](../firebase-remote-config/)
+- [@nativescript/firebase-storage](../firebase-storage/)
+
+## Installation
+
 ```cli
 npm install @nativescript/firebase-core
 ```
+## Configure Firebase for Android
+
+To configure Firebase for Android, visit [Add Firebase to your Android project](https://firebase.google.com/docs/android/setup) and follow the steps below. 
+
+- [Create a Firebase project](https://firebase.google.com/docs/android/setup#create-firebase-project)
+
+- [Register your app with Firebase](https://firebase.google.com/docs/android/setup#register-app)
+
+- [Add a Firebase configuration file](https://firebase.google.com/docs/android/setup#add-config-file) : Download the `google-services.json` file and add it to `App_Resources/Android/src`.
 
-## Usage
+## Configure Firebase for iOS
 
-### Android
-Ensure `google-services.json` file located in `App_Resources/Android/src`.
+To set up Firebase for iOS, visit [Add Firebase to your Apple project](https://firebase.google.com/docs/ios/setup) and follow the steps below:
+- [Create a Firebase project](https://firebase.google.com/docs/ios/setup#create-firebase-project)
+- [Register your app with Firebase](https://firebase.google.com/docs/ios/setup#register-app)
+-  [Add a Firebase configuration file](https://firebase.google.com/docs/ios/setup#add-config-file): Download the `GoogleService-Info.plist` file and add it to `App_Resources/iOS/`.
 
-### iOS
-Ensure `GoogleService-Info.plist` file located in `App_Resources/iOS`.
+## Use @nativescript/firebase-core
 
-### Initialize Default App
+### Instantiate Firebase and initialize a default app
 
+Import the `firebase` function and call it to create a NativeScript Firebase instance. Next, call the `initializeApp` method on the Firebase instance to instantiate the native [FirebaseApp](https://firebase.google.com/docs/reference/android/com/google/firebase/FirebaseApp).
+ 
 ```ts
 import { firebase } from '@nativescript/firebase-core'
 const defaultApp = await firebase().initializeApp();
 ```
 
-### Initialize Secondary App
+#### Initialize Secondary App
 
 ```ts
 import { firebase, FirebaseOptions } from '@nativescript/firebase-core'