Clean up outdated Firebase README (#5610) (#5612)

Author: ryanwilson

CoreOnly/README.md

@@ -3,78 +3,5 @@
 Simplify your iOS development, grow your user base, and monetize more
 effectively with Firebase services.
 
-Much more information can be found at [https://firebase.google.com](https://firebase.google.com).
-
-## Install a Firebase SDK using CocoaPods
-
-Firebase distributes several iOS specific APIs and SDKs via CocoaPods.
-You can install the CocoaPods tool on OS X by running the following command from
-the terminal. Detailed information is available in the [Getting Started
-guide](https://guides.cocoapods.org/using/getting-started.html#getting-started).
-
-```
-$ sudo gem install cocoapods
-```
-
-## Add a Firebase SDK to your iOS app
-
-CocoaPods is used to install and manage dependencies in existing Xcode projects.
-
-1.  Create an Xcode project, and save it to your local machine.
-2.  Create a file named `Podfile` in your project directory. This file defines
-    your project's dependencies, and is commonly referred to as a Podspec.
-3.  Open `Podfile`, and add your dependencies. A simple Podspec is shown here:
-
-    ```
-    platform :ios, '8.0'
-    pod 'Firebase'
-    ```
-
-4.  Save the file.
-
-5.  Open a terminal and `cd` to the directory containing the Podfile.
-
-    ```
-    $ cd <path-to-project>/project/
-    ```
-
-6.  Run the `pod install` command. This will install the SDKs specified in the
-    Podspec, along with any dependencies they may have.
-
-    ```
-    $ pod install
-    ```
-
-7.  Open your app's `.xcworkspace` file to launch Xcode. Use this file for all
-    development on your app.
-
-8.  You can also install other Firebase SDKs by adding the subspecs in the
-    Podfile.
-
-    ```
-    pod 'Firebase/AdMob'
-    pod 'Firebase/Analytics'
-    pod 'Firebase/Auth'
-    pod 'Firebase/Database'
-    pod 'Firebase/DynamicLinks'
-    pod 'Firebase/Firestore'
-    pod 'Firebase/Functions'
-    pod 'Firebase/InAppMessaging'
-    pod 'Firebase/Messaging'
-    pod 'Firebase/MLCommon'
-    pod 'Firebase/MLModelInterpreter'
-    pod 'Firebase/MLNLLanguageID'
-    pod 'Firebase/MLNLSmartReply'
-    pod 'Firebase/MLNLTranslate'
-    pod 'Firebase/MLNaturalLanguage'
-    pod 'Firebase/MLVision'
-    pod 'Firebase/MLVisionAutoML'
-    pod 'Firebase/MLVisionBarcodeModel'
-    pod 'Firebase/MLVisionFaceModel'
-    pod 'Firebase/MLVisionLabelModel'
-    pod 'Firebase/MLVisionObjectDetection'
-    pod 'Firebase/MLVisionTextModel'
-    pod 'Firebase/Performance'
-    pod 'Firebase/RemoteConfig'
-    pod 'Firebase/Storage'
-    ```
+Much more information can be found at
+[https://firebase.google.com/docs/ios/setup](https://firebase.google.com/docs/ios/setup).