Added README about Apple silicon Macs (#7057)

* Added README about Apple silicon Macs.

* Add link in README.

Author: ryanwilson

AppleSilicon.md

@@ -0,0 +1,49 @@
+# Apple Silicon Simulator Support
+
+If you're using Swift Package Manager or the zip file, everything should work for you
+using Xcode 12.0 or above. See the instructions below for CocoaPods and Carthage.
+
+## CocoaPods
+
+All source-based Firebase CocoaPods work as expected. Binary pods are listed below with the current
+status.
+
+### Analytics + GoogleAppMeasurement
+
+As of Firebase 7.2.0, FirebaseAnalytics and GoogleAppMeasurement provide a separate distribution of
+an XCFramework in order to work around an issue with CocoaPods and static XCFrameworks. This is a
+temporary workaround while Analytics is affected by the CocoaPods bug.
+
+When specifying which version of Firebase you'd like in your Podfile, append `-M1` to the version.
+See the following examples:
+
+```
+# Explicitly require the special `M1` tagged Firebase version.
+pod 'Firebase/Analytics', '~> 7.2.0-M1'
+
+# Do the same for any other Firebase pod used.
+pod 'Firebase/Database', '~> 7.2.0-M1'
+
+# You can also lock on the minor or major versions like so:
+pod 'Firebase/Analytics, '~> 7.2-M1'
+pod 'Firebase/Analytics, '~> 7-M1'
+```
+
+The CocoaPods issue has been fixed in CocoaPods/CocoaPods#10234 but has not been included in a
+CocoaPods release yet.
+
+### Performance
+
+As of Firebase 7.2.0, FirebasePerformance uses an XCFramework for distribution that works with
+Apple silicon.
+
+### FirebaseML
+
+FirebaseML does not yet work with the simulator on Apple silicon Macs.
+
+## Carthage
+
+XCFrameworks are required to include the arm64 slice for iOS devices and the macOS simulator for
+Macs running on Apple silicon. Unfortunately, Carthage does not support XCFrameworks yet which
+prevents us from being able to include support. See Carthage/Carthage#2799 for progress.
+

README.md

@@ -45,7 +45,8 @@ See the subsections below for details about the different installation methods.
 ### Standard pod install
 
 Go to
-[https://firebase.google.com/docs/ios/setup](https://firebase.google.com/docs/ios/setup).
+[https://firebase.google.com/docs/ios/setup](https://firebase.google.com/docs/ios/setup). If you
+have a new Mac with an Apple silicon chip, please see [these instructions](AppleSilicon.md).
 
 ### Swift Package Manager (Beta)
 
@@ -88,7 +89,8 @@ pod 'FirebaseMessaging', :path => '/path/to/firebase-ios-sdk'
 ### Carthage (iOS only)
 
 Instructions for the experimental Carthage distribution are at
-[Carthage](Carthage.md).
+[Carthage](Carthage.md). If you have a new Mac with an Apple silicon chip, please see
+[these instructions](AppleSilicon.md).
 
 ### Using Firebase from a Framework or a library