Update the link for iOS demo app in README.md (pytorch#27145)

Summary:
Update the link for iOS demo app in README.md
Pull Request resolved: pytorch#27145

Differential Revision: D17746591

Pulled By: xta0

fbshipit-source-id: 6f49a0daddc8b79804e1b8487ba1db3807a3f481

Author: xta0

ios/README.md

@@ -17,12 +17,12 @@ For Objective-C developers, simply import the umbrella header
 #import <LibTorch/LibTorch.h>
 ```
 
-For Swift developers, you need to create an Objective-C class as a bridge to call the C++ APIs. We highly recommend you to follow the [Image Classification](https://github.com/pytorch/examples) demo where you can find out how C++, Objective-C and Swift work together. 
+For Swift developers, you need to create an Objective-C class as a bridge to call the C++ APIs. We highly recommend you to follow the [Image Classification](https://github.com/pytorch/ios-demo-app/tree/master/PyTorchDemo) demo where you can find out how C++, Objective-C and Swift work together. 
 
 ### Disable Bitcode 
 
 Since PyTorch is not yet built with bitcode support, you need to disable bitcode for your target by selecting the **Build Settings**, searching for **Enable Bitcode** and set the value to **No**.
 
 ## LICENSE
 
-PyTorch is BSD-style licensed, as found in the LICENSE file.
+PyTorch is BSD-style licensed, as found in the LICENSE file.