Fix the order of parameters for the Cycle API readme.

Hey! Noticed a typo in the `Readme.md` file while checking out this library and just thought I'd send a quick pull request.

It seems the order of parameters for the `Cycle` constructor were inconsistent between the API Readme notes and the code:

https://github.com/Automattic/trace-json/blob/master/index.js#L44

Thanks!