[eslint-plugin] Minor: fix link in readme
[eslint-plugin] Minor: fix link in readme

Summary:
Fix the link.

Changelog: [internal]

Reviewed By: mroch

Differential Revision: D30919213

fbshipit-source-id: ec06d24c4f711da7e3313e4194d55b5717633591

mroch/flow,mroch/flow,facebook/flow,facebook/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow,mroch/flow,mroch/flow,facebook/flow,facebook/flow