> shouldn't the docs be made available for the currently maintained version of python?

Problem is the Tk version (which underpins tkinter) varies by distribution. Currently, Windows and MacOS Intel installers are packaged with 8.6.8, while MacOS Universal2 is soon to be packaged with a head later than 8.6.10. The situation gets worse on Linux, where different distros provide very different versions (CentOS 7, for example, runs Tk 8.5.13 which was released back in 2012). As the available options vary by version, we face an issue of what we actually describe in the docs.

As a side note, Shipman's docs are now also hosted at tkdocs.com/shipman, a site maintained by Mark Roseman, which should be more reliable than a github.io page (see issue37149 - he will also handle any copyright claims, etc. that may arise that meant we couldn't host it on docs.python.org).