"Тока" is a misspelling of "только" which you frequently encounter because in fast speech, that "ль" doesn't get pronounced.

Sometimes, it's deliberate; the writer is going for the effect of transcribing colloquial speech - like in English, you might write "innit" instead of "isn't it" to render a casual spoken conversation.

And sometimes, it's a sign of a illiteracy - like in English, when people write "should of" instead of "should have" because it sounds the same and they don't know any better.

Given that the tagline for the project is "Fusion Reactor for Rust," I'd guess that the project's name is designed to read to English speakers as "Tokamak" while maintaining a "Russian flavor."

EDIT: Not being a Russian speaker, I completely misunderstood this comment -- I apologize for my blithe ignorance.