docs: Update project documentation

[volodymyr-chekyrta]

This PR updates the project README file, introduces documentation on configuration management and APIs compatibility.

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[k1rill]

LGTM

[HamzaIsrar12]

Thanks for leading this effort. 🚀 Document looks good overall, just a few minor issues and concerns I've noticed.

[HamzaIsrar12]

Do we need to mention other features like Agreement Urls, Discovery, Program etc? 🤔

[volodymyr-chekyrta]

I don't feel it's necessary to mention them now, since we store their default keys in the config.yaml file.
We can add documentation on them later.

[volodymyr-chekyrta]

@HamzaIsrar12 thank you for the review!
All feedback has been addressed, and PR is ready for another pass 🚀

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