[docs] update installation instructions now that we have a pip package (#95)

README.md

@@ -80,14 +80,20 @@ if __name__ == "__main__":
 
 Normal installation:
 ```bash
-pip install .
+pip install fairscale
 ```
 
 Development mode:
 ```bash
+cd fairscale
+pip install -r requirements.txt
 pip install -e .
 ```
 
+# Testing
+
+We use circleci to test on PyTorch versions 1.5.1 and 1.6.0 and CUDA version 10.1. Please create an [issue](https://github.com/facebookresearch/fairscale/issues) if you are having trouble with installation.
+
 ## Contributors
 
 See the [CONTRIBUTING](CONTRIBUTING.md) file for how to help out.