iOS,docs: Update iOS symbolication docs (flutter#54494)

As of flutter/flutter#153215, end user app archives now include symbols for the Flutter framework by default. So manual symbolication is no longer required.

For engine developers and others who still need to deal with manual symbols, they can now be found in the Flutter tool cache and can thus be obtained from there if required.

Issue: flutter/flutter#116493

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

docs/Crashes.md

@@ -1,6 +1,8 @@
 ## Symbolicating stack traces for engine crashes
 
-The easiest way to symbolicate stack traces for Android and iOS is running the [dart_ci symbolizer locally](https://github.com/dart-lang/dart_ci/blob/main/github-label-notifier/symbolizer/README.md#using-this-locally). If that is not an option, the steps below explain how to do it manually.
+iOS app archives produced using Flutter 3.24 or later embed engine debugging symbols and thus crashes are symbolicated by default.
+
+The easiest way to symbolicate stack traces for Android and older iOS apps is to run the [dart_ci symbolizer locally](https://github.com/dart-lang/dart_ci/blob/main/github-label-notifier/symbolizer/README.md#using-this-locally). If that is not an option, the steps below explain how to do it manually.
 
 ### Android
 
@@ -88,7 +90,25 @@ adb logcat | ~/dev/engine/src/third_party/android_tools/ndk/prebuilt/linux-x86_6
 
 ### iOS
 
-The dSYM file for `Flutter.framework` (which is the Flutter Engine) for ios-release builds can be downloaded from Google Cloud Storage. Follow the steps from the Android section in this guide, but in the last step use a download url following this schema: `https://storage.cloud.google.com/flutter_infra_release/flutter/38a646e14cc25f5a56a989c6a5787bf74e0ea386/ios-release/Flutter.dSYM.zip` (replace the engine hash with your hash).
+Since Flutter 3.24, symbols can be found in the Flutter framework's artifact
+cache, within the xcframework bundle at
+`bin/cache/artifacts/engine/ios-release/Flutter.xcframework`.
+
+  * Symbols for device builds are in the `ios-arm64/dSYMs/Flutter.framework.dSYM` bundle.
+  * Symbols for simulator builds are in the `ios-arm64_x86_64-simulator/dSYMs/Flutter.framework.dSYM` bundle.
+
+For versions prior to Flutter 3.24, the dSYM bundle can downloaded from Google
+Cloud Storage. Follow the steps from the Android section in this guide, but in
+the last step use a download url following this schema:
+`https://storage.cloud.google.com/flutter_infra_release/flutter/38a646e14cc25f5a56a989c6a5787bf74e0ea386/ios-release/Flutter.dSYM.zip`
+(replace the engine hash with your hash).
+
+For release since Flutter 3.24, these symbols are no longer uploaded as a
+separate archive and should be obtained from the artifact cache as described
+above. The artifact cache can be downloaded direcly using a URL following this
+schema:
+`https://storage.googleapis.com/flutter_infra_release/flutter/c11fe483947c95553610ab59210af643f031f5f4/ios-release/artifacts.zip`
+(replace the engine hash with your hash).
 
 #### Symbolicating local builds