update the format grammar
@@ -342,7 +342,9 @@ static struct extractor_specifier * format_parse(char *format, size_t * n) {
/*
* format grammar:
- * ([key1]|[][number])+(%<d|ld\lld|f\lf|b\s\S>)
+ * ([key1]|[]|[<n>])+%(d|ld|lld|f|lf|b|<n>s|<n>S)
+ *
+ * n is an integer
*
* usage:
* json_scanf2(str, "[k1][k2]%d", &i);
