Emphasize typo in the source file

This is actual field name in the exported CSV.  Better to not fix it and
create confusion later.

gcconv.py

     # (c) Account number
     # (d) Account Name
     # (e) Transaction Category
-    # (f) Accocunt Number
+    # (f) Accocunt Number [SIC]
     # (g) Name of Account
     # (h) Transaction type
     # (i) Message