OX6 and AppSuite code is improving continuously. Therefore, APIs and SPIs are bound to change. Changes are publicized cautiously with each now release, depending on the maturity of the module and, depending on that, the stability of the existing documentation.
To ensure you know which feature is enabled with which version, here is an explanation on how the versioning of our documentation works:
If you encounter an article link which does not have a version number, this goes to the lastest version of the article. When linking articles, you should usually avoid using a version number (unless you are pointing to a specific version, of course), thereby always linking the latest article.
Note: In case there is only one article and it never had a precedent, the article title will not have a version number yet. Otherwise, the article without one will be a redirect to the latest version.
Writing something that is easy on the user is a slightly more complicated. But do not worry, in the worst case, someone will clean up after you. The detailed explanation can be found here: Help:Howto#Numbering_and_versioning