Add comment about the API Gateway payload format

Author: seratch

slack_bolt/adapter/aws_lambda/handler.py

@@ -75,6 +75,12 @@ def handle(self, event, context):
 
 
 def to_bolt_request(event) -> BoltRequest:
+    """Note that this handler supports only the payload format 2.0.
+    This means you can use this with HTTP API while REST API is not supported.
+
+    Read https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-develop-integrations-lambda.html
+    for more details.
+    """
     body = event.get("body", "")
     if event["isBase64Encoded"]:
         body = base64.b64decode(body).decode("utf-8")