Add ID-based cancellation to README

README.md

@@ -229,6 +229,8 @@ networking.POST("/upload", parameterType: .Custom("application/octet-stream"), p
 
 ## Cancelling a request
 
+### Using path
+
 Cancelling any request for a specific path is really simple. Beware that cancelling a request will cause the request to return with an error with status code -999.
 
 ```swift
@@ -240,6 +242,27 @@ networking.GET("/get") { JSON, error in
 networking.cancelGET("/get")
 ```
 
+### Using request identifier
+
+Using `cancelPOST("/upload")` would cancel all POST request for the specific path, but in some cases this isn't what we want. For example if you're trying to upload two photos, but the user requests to cancel one of the uploads, using `cancelPOST("/upload") would cancell all the uploads, this is when ID based cancellation is useful.
+
+```swift
+let networking = Networking(baseURL: "http://httpbin.org")
+
+// Start first upload
+let firstRequestID = networking.POST("/upload", parts: ...) { JSON, error in
+    //...
+}
+
+// Start second upload
+let secondRequestID = networking.POST("/upload", parts: ...) { JSON, error in
+    //...
+}
+
+// Cancel only the first upload
+networking.cancel(firstRequestID)
+```
+
 ## Faking a request
 
 Faking a request means that after calling this method on a specific path, any call to this resource, will return what you registered as a response. This technique is also known as mocking or stubbing.