style: fix; add note

Author: fubuloubu

tests/unit/test_erc7201.py

@@ -40,10 +40,11 @@ def test_erc7201_hex_namespace():
 
 
 @pytest.mark.parametrize(
-    "namespace,expected",
-    [
-         ("example.main", 0x183a6125c38840424c4a85fa12bab2ab606c4b6d0e7cc73c0c06ba5300eab500),
-    ],
+         # see: https://eips.ethereum.org/EIPS/eip-7201#reference-implementation
+         (
+             "example.main",
+              0x183a6125c38840424c4a85fa12bab2ab606c4b6d0e7cc73c0c06ba5300eab500,
+         ),
 )
 def test_erc7201_reference(namespace, expected):
     assert erc7201_storage_slot(namespace) == expected