docs: Update install from sources using setuptools

[ceyusa]

Updates install documentation since setup.py file doesn't exist anymore.

Pull Request Checklist

• Ensured tests pass and (if applicable) updated functional test output
• Conformed to code style guidelines by running appropriate linting tools
• Added tests for changed code
• Updated documentation for changed code

None of these checkups apply.

[justinmayer]

Thanks to @ceyusa for the contribution and to @pauloxnet for reviewing 😊