Update iOS.md (#360)

Author: mikekgfb

docs/iOS.md

@@ -3,6 +3,19 @@
 Check out the [tutorial](https://pytorch.org/executorch/main/llm/llama-demo-ios.html) on how to build the iOS demo app running your
 PyTorch models with [ExecuTorch](https://github.com/pytorch/executorch).
 
+Once you can run the app on you device,
+1 - connect the device to you Mac,
+2 - copy the model and tokenizer.bin to the iOS Llama app
+3 - select the tokenizer and model with the `(...)` control (bottom left of screen, to the left of the text entrybox)
+
+
+Detailed step by step in conjunction with ExecuTorch iOS build, to run on
+simulator for iOS.
+
 <a href="https://pytorch.org/executorch/main/_static/img/llama_ios_app.mp4">
   <img src="https://pytorch.org/executorch/main/_static/img/llama_ios_app.png" width="600" alt="iOS app running a LlaMA model">
 </a>
+
+<--
+<A HREF=https://github.com/pytorch/executorch/blob/main/docs/source/_static/img/llama_ios_app.png>torchchat on iOS</A>
+-->