fix(docs): add missing options synthax on isISO8601 validator (validatorjs#1860)

Author: leonardovillela

README.md

@@ -129,7 +129,7 @@ Validator                               | Description
 **isIPRange(str [, version])**          | check if the string is an IP Range (version 4 or 6).
 **isISBN(str [, version])**             | check if the string is an ISBN (version 10 or 13).
 **isISIN(str)**                         | check if the string is an [ISIN][ISIN] (stock/security identifier).
-**isISO8601(str)**                      | check if the string is a valid [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) date. <br/>`options` is an object which defaults to `{ strict: false, strictSeparator: false }`. If `strict` is true, date strings with invalid dates like `2009-02-29` will be invalid. If `strictSeparator` is true, date strings with date and time separated by anything other than a T will be invalid.
+**isISO8601(str [, options])**          | check if the string is a valid [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) date. <br/>`options` is an object which defaults to `{ strict: false, strictSeparator: false }`. If `strict` is true, date strings with invalid dates like `2009-02-29` will be invalid. If `strictSeparator` is true, date strings with date and time separated by anything other than a T will be invalid.
 **isISO31661Alpha2(str)**               | check if the string is a valid [ISO 3166-1 alpha-2](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) officially assigned country code.
 **isISO31661Alpha3(str)**               | check if the string is a valid [ISO 3166-1 alpha-3](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-3) officially assigned country code.
 **isISO4217(str)**                      | check if the string is a valid [ISO 4217](https://en.wikipedia.org/wiki/ISO_4217) officially assigned currency code.