Update barcode/charsets/ean.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: dekoza

barcode/charsets/ean.py

@@ -6,8 +6,8 @@
 from barcode.charsets.addons import ADDON_SEPARATOR
 from barcode.charsets.addons import ADDON_START
 
-# Note: Addon codes use CODES["A"] and CODES["B"] defined below
-
+# Note: Addon codes are defined in barcode.charsets.addons, but they use the
+# same A/B digit encodings as CODES["A"] and CODES["B"] defined below.
 EDGE = "101"
 MIDDLE = "01010"
 CODES = {