Update README.md

Add another option for: pip install nemo_toolkit['all']

README.md

@@ -165,6 +165,10 @@ See the [model architecture](#model-architecture) section and [NeMo documentatio
 
 To train, fine-tune or play with the model you will need to install [NVIDIA NeMo](https://github.com/NVIDIA/NeMo). We recommend you install it after you've installed latest Pytorch version.
 ```
+pip install nemo_toolkit['all']
+'''
+'''
+(if it causes an error): 
 pip install nemo_toolkit[all]
 ```