Incorrect example in README

[rubikskub]

Using this example code in the README for subscribing we received a 404 response from GCP:

subscription = %Kane.Subscription{topic: %Kane.Topic{name: "my-topic"}

Changing it to:

subscription = %Kane.Subscription{name: "my-topic"}

seems to work better.

[peburrows]

I think the most correct syntax is actually somewhere between those two:

%Kane.Subscription{
  name: "my-sub",
  topic: %Kane.Topic{
    name: "my-topic"
  }
}

I'll update the README to fix things.

[peburrows]

b88f364 should fix this.