Minor changes

• Loosened Python version requirements from 3.9 to 3.7

Minor changes:

• Clarification on documentation

Mostly documentation:

• Updated README markdown
• Added instructions to install from PyPi
• Removed duplicate language around installing from source

What's Changed

• Create CODE_OF_CONDUCT.md by @furritos in #1

New Contributors

• @furritos made their first contribution in #1

Full Changelog: https://github.com/furritos/flask-simple-crypt/commits/v0.2.9