Change tests/README.md to reflect repo structure change (#13437)

Co-authored-by: Jirka Borovec <[email protected]>
Co-authored-by: Carlos Mocholí <[email protected]>

Author: 3 people

tests/README.md

@@ -9,10 +9,11 @@ To setup a local development environment, install both local and test dependenci
 
 ```bash
 # clone the repo
-git clone https://github.com/PyTorchLightning/pytorch-lightning
-cd pytorch-lightning
+git clone https://github.com/Lightning-AI/lightning.git
+cd lightning
 
 # install required depedencies
+export PACKAGE_NAME=pytorch
 python -m pip install ".[dev, examples]"
 # install pre-commit (optional)
 python -m pip install pre-commit