TypeScript definition does not include opt

[patarapolw]

https://www.npmjs.com/package/fast-json-stable-stringify#options should be in

declare module 'fast-json-stable-stringify' {
  function stringify(obj: any): string;
  export = stringify;
}

I also need replacer, but this is another topic.

[marceliwac]

As extremely simple as it is, I'm struggling with checking out the fork for this repository and submitting a PR. The needed changes are:

index.d.ts:

declare module 'fast-json-stable-stringify' {
  function stringify(obj: any, options: object): string;
  export = stringify;
}

[sxwei123]

Added in this PR: #41