RN fixture update: Update the iOS instructions to add required files/settings

Author: Cawllec

test/react-native/TESTING.md

@@ -161,7 +161,9 @@ Remove
     ```
 
 1. Open `ios/reactnative.xcworkspace` in Xcode
+    1. Add `BugsnagModule.h` and `BugsnagModule.m` from `../../ios-modules` to the `reactnative/reactnative` group
     1. Add a new Group called `Scenarios` beneath `reactnative/reactnative`
     1. Add all files in `../../ios-modules/Scenarios` to the new group
     1. Xcode may prompt to add a bridging header for Swift.  Cancel this and instead:
     1. Set Build Settings -> Swift Compiler - General -> Objective-C Bridging Header to `../../ios-module/Scenarios/Scenario.h`
+    1. Set Signing & Capabilities -> Build team to the shared Bugsnag iOS build team