We centralized a decentralized version control system.

$2 billion to the first person to draft a decentralised git coin WhitePaper

I think you just did.

No. We need a proper whitepaper explaining how to make GitHub decentralized with blockchain tokenization using distributed smart-contracts. ;)

(Did I forget any important buzzword?)

It exist! Not a whitepaper, but at least a Medium article: https://medium.com/@alexberegszaszi/mango-git-completely-dec.... Ethereum + IPFS/Swarm as backend for Git.

Source code is currently unavailable as it is hosted on ... drum roll ... GitHub: https://github.com/axic/mango.