add docstring explaining type alises

Author: alexander-alderman-webb

sentry_sdk/integrations/anthropic.py

@@ -372,6 +372,8 @@ def _wrap_synchronous_message_iterator(
     response_id = None
 
     for event in iterator:
+        # Message and content types are aliases for corresponding Raw* types, introduced in
+        # https://github.com/anthropics/anthropic-sdk-python/commit/bc9d11cd2addec6976c46db10b7c89a8c276101a
         if not isinstance(
             event,
             (
@@ -437,6 +439,8 @@ async def _wrap_asynchronous_message_iterator(
     response_id = None
 
     async for event in iterator:
+        # Message and content types are aliases for corresponding Raw* types, introduced in
+        # https://github.com/anthropics/anthropic-sdk-python/commit/bc9d11cd2addec6976c46db10b7c89a8c276101a
         if not isinstance(
             event,
             (