uber / causalml

Describe the bug
Add the below conda installation sequence to docs/installation.rst (previously removed from README.md).

causalml/README.md

Lines 112 to 120 in 028c63c

    
           ### Create a clean conda environment 
        
           ``` 
        
           conda create -n causalml-py38 -y python=3.8 
        
           conda activate causalml-py38 
        
           conda install -c conda-forge cxx-compiler 
        
           conda install python-graphviz 
        
           conda install -c conda-forge xorg-libxrender 
        
           ```

To Reproduce
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Expected behavior
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Screenshots
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Environment (please complete the following information):
N/A

Additional context
N/A

	### Create a clean conda environment

	```
	conda create -n causalml-py38 -y python=3.8
	conda activate causalml-py38
	conda install -c conda-forge cxx-compiler
	conda install python-graphviz
	conda install -c conda-forge xorg-libxrender
	```

add clean conda env install sequence to docs/installation.rst