Add Pypi long description

[sohang3112]

In the Pypi package, it shows Author of this package has not provided a project description.

To fix this:

• setup.py should be modified to include contents of README.md as long_description in setup() function. Important: long_description_content_type="text/markdown" should be set in setup() function.
• ensure README.md and icon.png are included in the Pypi package zip (using MANIFEST.in)

[sohang3112]

@tyiannak Please add long description (README) to Pypi to make this package more approachable.