Update readme to use the latest release. (#4407)

Summary: .

Differential Revision: D60204312

Co-authored-by: Anthony Shoumikhin <shoumikhin@meta.com>

Author: kirklandsign

examples/demo-apps/apple_ios/ExecuTorchDemo/README.md

@@ -44,9 +44,8 @@ Follow the [Setting Up ExecuTorch](https://pytorch.org/executorch/stable/getting
 tutorial to configure the basic environment:
 
 ```bash
-git clone -b release/0.2 https://github.com/pytorch/executorch.git
+git clone https://github.com/pytorch/executorch.git -b release/0.3 --recursive
 cd executorch
-git submodule update --init
 
 python3 -m venv .venv && source .venv/bin/activate