404 Response for Index Page

[Sircular]

Currently, making a GET request to / gets a 404 response. This makes it more difficult for my use case, with Consul service discovery; I'd like to be able to use HTTP health checks without hitting the /metrics endpoint every 10 seconds.

I'm willing to make a PR since this is a fairly small change; let me know if it would be something you'd be interested in merging.