Alternative installation with conda

Hi, I had some trouble installing using the venv. I'm used to conda, so eventually created a conda environment.

If users prefer to use conda than virtual environments, the installation instructions would be:

Clone the repository
Navitate to the repository
Download environment.yml, and move it to the repository (inside the pysn-digest folder)
Assuming conda is installed, type conda env create -f environment.yml . The dependencies etc will be installed. This will take some time.
The environment can then be activated by typing conda activate pysn_env
After the environment is activated type python digest.py to run the script. (You'll need to ensure user_settings.json is configured correctly)

This has only been tested on Windows 10