Add description how to setup development environment

[pavelee]

Feature Description

Description how to setup development environment

It should be implemented because...

To clarify how to run app for development, especially part about your GitHub token required to signing

Describe alternatives you've considered

Could be something like https://github.com/facebook/docusaurus but at this moment description in README is enough

Additional context

I spend some extra time to figure out how to singing on development environment

[pavelee]

nvm, I found it in https://github.com/Balastrong/github-stats/blob/main/CONTRIBUTING.md

closing!

[Balastrong]

If you think something is missing or is not clear enough, feel free to open a PR or an issue to discuss it :)