That "version" field in the documentation for any particular API endpoint is referring to the endpoint version number. (This is distinct from the API version number, which is "2" for the current version of the API itself.)
The endpoint version is included at the end of the API route. When the endpoint is still on version 1, it is omitted.
As an example, refer to the /2/files/move_v2 route. That is endpoint version 2, signified by "_v2", of the files/move endpoint (on API version 2, signified by "/2/").
