MiddlewareWithConfig method in comment but not exists

[roger-codina]

Hi guys,

If I am not mistaken, I think that this comment refers to an old method or a not implemented one: https://github.com/newrelic/go-agent/blob/c6110878eac69902e7c5d8203aa64c4e3ea4cae6/v3/integrations/nrecho-v4/nrecho.go#L73

The only way to create the middleware handler is calling the Middleware function using a *newrelic.Application as the first argument and passing as variadic arguments ConfigOption types.

So, I think that the comment should be fixed to document the current behaviour of the function or implement that method :)

Cheers!