ref(sdk-crashes): Fix stacktrace rule in docs (#60776)

Clarify to add +group to the stacktrace rule in code comments and
readme.

src/sentry/utils/sdk_crashes/README.rst

@@ -28,7 +28,7 @@ If the event is fatal, caused by one of our SDKs,
 the code strips away most of the data based on an allow list and stores the event to a dedicated Sentry project. The event_stripper only keeps
 SDK and system library frames. For grouping to work correctly, the event_stripper sets in_app to true for all SDK frames, but the grouping
 config will change it to in_app false for all Cocoa SDK frames. To not change the grouping logic, we add the following stacktrace rule
-``stack.abs_path:Sentry.framework +app`` to the configured in project with the id configured in the option ``issues.sdk_crash_detection.cocoa.project_id``.
+``stack.abs_path:Sentry.framework +app +group`` to the configured in project with the id configured in the option ``issues.sdk_crash_detection.cocoa.project_id``.
 
 You can turn the feature on or off in https://sentry.io/_admin/options. The option name is ``issues.sdk-crash-detection`` and the feature name is ``organizations:sdk-crash-detection``.
 Furthermore, you can change the project to store the crash events and the sample rate per SDK with the options ``issues.sdk_crash_detection.cocoa.project_id`` and ``issues.sdk_crash_detection.cocoa.sample_rate``.

src/sentry/utils/sdk_crashes/event_stripper.py

@@ -167,7 +167,7 @@ def _strip_frames(
     `SDKCrashDetectorConfig.sdk_frame_config.path_replacer` and
     `SDKCrashDetectorConfig.sdk_frame_path_default_replacement_name`.
 
-    For example, Cocoa only uses `Sentry.framework` as a replacement path, so we must add the rule `stack.abs_path:Sentry.framework +app` to it's project in Sentry.
+    For example, Cocoa only uses `Sentry.framework` as a replacement path, so we must add the rule `stack.abs_path:Sentry.framework +app +group` to it's project in Sentry.
     """
 
     def strip_frame(frame: MutableMapping[str, Any]) -> MutableMapping[str, Any]: