Briefly document Fio loader.

doc/bank.md

@@ -82,3 +82,14 @@ Returns true if given combination of ```acc```/```bc``` is in
 
 ### Bank Fio
 
+    (import bank-fio)
+
+This module implements parser/loader for Fio account statements in CSV
+format.
+
+    (bank-fio-parse fn)
+
+* ```fn``` - path to given file with CSV export
+
+Uses ```csv-parse``` from ```util-csv``` module and loads the contents
+into ```bank-account``` structure with list of ```bank-transaction```s.