adding description about proxys to readme

[fnaquira]

I was struggling before finding this on the issue section. I think it should be on the main readme because some people are still new to some params on Express.

[coveralls]

Coverage remained the same at 97.543% when pulling aa7d1b1 on fnaquira:readme-proxy into bc48c35 on AdamPflug:master.

[AdamPflug]

I think you're right that this is worth including. Could you also include a link to the relevant express documentation and a warning that the value "true" would allow for bypass of the express brute functionally https://expressjs.com/en/guide/behind-proxies.html

[fnaquira]

Now it is. Thank you for the consideration.

[AdamPflug]

Thanks for contributing :)