The WHATWG (Web Hypertext Application Technology Group) calls the core markup part of the HTML5 ecosystem just HTML. No version. The spec is a living standard like the English language, which makes sense to me. Nobody refers to the English of the sixties (“far out,” “can you dig it?”) as English 8, say, and the English of today (“to text,” “to Google”) as English 10 or 11.
It probably means no browser will ever be fully compliant with the HTML spec but then has any browser ever been fully compliant with a new spec? With the ease and frequency of auto-updates, modern browsers can adapt and evolve with the spec.
The W3C (World Wide Web Consortium) still calls the markup language HTML5 rather than just HTML, but its spec is basically the same as the WHATWG’s. You’ll find the WHATWG spec here.