Added documentation of pyDataverse conda installation (again)

[PennyHow]

These are minor edits to pyDataverse docs to include documentaion on the new conda install, as discussed here - #159

Platforms

• OS: NAME, VERSION, 64/32bit
  • Linux 64-bit
• pyDataverse: VERSION
  • v0.3.1
• Python: VERSION
  • Python 3.8
• Dataverse: VERSION
  • NA

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  • docs
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  • Updating pyDataverse docs with information about how to install the package with conda
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Others

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  • If anyone else has anything to add then please do. Also, I added the conda install instructions to the index.rst page as well as the installation page. I know though that you might want to keep the front page simplified and only include the conda install on the installation page (along with the instructions on installing with pipenv). If so, then please feel free to alter accordingly.

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Closes #159

[JR-1991]

Looks good to me! Thanks for submitting 🙌