Missing documentation around remote middleware

[benjih]

Having a look at the documentation, middleware makes no reference to running it remotely.

We should add this as well as an explanation as to why you might do this over the standard way of running middleware.

You can configure middleware to run remotely. To do this, you need to provide a URL as middleware.

hoverctl middleware --remote <middleware-url>

When implementing middleware in this way, Hoverfly will POST the same RequestResponsePair JSON it would send to stdin for standard middleware. Hoverfly will then expect a 200 response will the same RequestResponsePair JSON it would read from stdout from standard middleware.

[benjih]

There is now documentation for HTTP middleware.