Updated the documentation to point the Pact Broker method to the brok…

[lmasterman]

…er root URI as the expected relationships do not exist at the pact file itself

[bethesque]

Hm. That doesn't seem right. Perhaps we need to alias that method? When fetching a particular pact, it makes sense to have a method called "PactURI" (as the other libraries do) but when fetching the general pacts for verification from the broker, I would expect to set a "PactBrokerBaseURI" (as the other libraries do). Can we make this happen?

[lmasterman]

Yeah, I realised it was incorrect just after submitting the pull request, the PactBroker() method takes a base Uri, my confusion came from muddling two separate documentation sources on setting up the pact-net library with a broker and thinking the full Uri including path was sent to the PactBroker() method, it would perhaps be made clearer if there was a commented or case for utilising the broker method instead of PactUri() here?

[bethesque]

There are two use cases - one where you verify a specific pact at a known URL (from the webhook, when a pact changes) and one where you're verifying all the pacts for a provider (when the provider changes).

I've got a request open to make these docs clearer #301