Add ask to accepted flags

Again, the list was generated via the manpage and as this is
undocumented it was forgotten.

parser.go

@@ -349,6 +349,7 @@ func formatArg(arg string) string {
 func isArg(arg string) bool {
 	switch arg {
 	case "-", "--":
+	case "ask":
 	case "D", "database":
 	case "Q", "query":
 	case "R", "remove":