message: Update transformExchange signature in README
diff: @@ -266,12 +266,12 @@ const defaultCache = store => {
  #### Options
  | Name | Value | Description |
  -| ----------------- | -------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
  +| ----------------- | ----------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
  | url | `string` | The URL that the Client should connect to _(required)_ |
  | initialCache | `object` | An initial state for your cache if you are using the default cache. This probably won't get much play until SSR is implemented |
  | cache | `ICache` | Instance of an `ICache` if you want to build your own custom one built with something like `AsyncStorage`. You can read more about how to create one of these above. |
  | fetchOptions | `object` or `() => object` | Options provided to the internal `fetch` calls which can either be an object or a function if you want to provide dynamic values like a token header. |
  -| transformExchange | `IExchange => IExchange` | A function that accepts the default "Exchange" and returns a new one. Use this to customise how the client handles GraphQL requests. |
  +| transformExchange | `(IExchange, IClient) => IExchange` | A function that receives the default "Exchange" and the client, and returns a new exchange. Use this to customise how the client handles GraphQL requests. |
  #### Description
  @@ -507,7 +507,7 @@ const funExchange = forward => operation =>
  const client = new Client({
  url: 'http://localhost:3000/graphql',
  - transformExchange: exchange => funExchange(exchange),
  + transformExchange: (exchange, _client) => funExchange(exchange),
  });
  ```
  