PyPI and GitHub Actions. Closes #43

[edavalosanaya]

Hello,

This PR includes the following:

Added GitHub actions workflow for automatic release of PyPI package. The GitHub action workflow will not run every time there is a push to master. Instead, it will run when you add a new tag to your repo. This allows you to push new changes to master and once you are ready to publish a new version, all you need to do is update the version number (in pyproject.toml) and create a new tag. Here is a StackOverflow forum that explains how to create new Git tags: here.

Key things to consider when publishing to PyPI:

1. Update pyproject.toml's version value to a new version (e.g. v0.0.2) when publishing new version. Don't try to publish v0.0.1 when v0.0.1 is already in PyPI (this will cause the workflow to fail). For the first time, you don't need to change anything.
2. Make sure that you have added your PyPI secret key to GitHub (Tutorial Here)

Also, this PR includes changes to the README.md, added doc-building dependencies to pyproject.toml, and build the docs with the latest README.md (might want to triple-check that I didn't build bad docs).