address review comments: 1. add arg help info; 2. add mutable buffer partition log

Author: yifan_shen3

backends/apple/coreml/partition/coreml_partitioner.py

@@ -92,6 +92,13 @@ def partition(self, exported_program: ExportedProgram) -> PartitionResult:
 
         tag_constant_data(exported_program)
         if self.take_over_mutable_buffer:
+            logger.info(
+                "Core ML partitioner will take over torch mutable buffer as Core ML state, "
+                "so if your model contains mutable buffer, "
+                "then you will need MacOS15+/iOS18+ to execute. "
+                "If you want your mutable buffer model to be compatible with older OS, "
+                "then please set `take_over_mutable_buffer=False`"
+            )
             tag_mutated_buffer(exported_program)
 
         return PartitionResult(

examples/models/llama2/export_llama_lib.py

@@ -281,7 +281,11 @@ def build_args_parser() -> argparse.ArgumentParser:
     parser.add_argument("-V", "--vulkan", action="store_true")
     parser.add_argument("--mps", action="store_true")
     parser.add_argument("--coreml", action="store_true")
-    parser.add_argument("--coreml-enable-state", action="store_true")
+    parser.add_argument(
+        "--coreml-enable-state",
+        action="store_true",
+        help="This option is only for coreml, and is only supported for MacOS15+/iOS18+",
+    )
     parser.add_argument(
         "--qnn",
         action="store_true",