Every page of the documentation exists in English, Polish and Ukrainian, and each version has its own address. Until now that address did not decide what you saw — the language stored from an earlier visit did. Opening a Ukrainian documentation link with Polish stored took you to the Polish version of the same page, and a link sent to a colleague or a customer behaved the same way for them. This affected most of the translated pages.
From now on the address decides. A documentation link opens the version it names, whoever follows it and whatever language they chose before, so a link you send is the page the recipient reads. The same applies to search engines, which until now were turned away from most documentation pages and could not offer them in their results.
The language selector at the top of the page changes with it. On a documentation page it now takes you to that page in the language you pick, instead of reloading the page you are already on. Where a page has no version in the chosen language, your choice is remembered and the page stays as it is, rather than leading to an address that does not exist. Everywhere else on the site the selector behaves exactly as before.