Add README section explaining how to enable auto-discovery over CORS (#307)
Add README section explaining how to enable auto-discovery over CORS (#307)

As noted in #303, our documentation does not cover how to enable the
REST API to be discovered with a cross-origin request. This PR adds
a new section to the readme to explain the process.

Fixes #303
kadamwhite/wordpress-rest-api,WP-API/node-wpapi,kadamwhite/wordpress-rest-api,WP-API/node-wpapi,kadamwhite/wordpress-rest-api