It seems premature to worry about 8.7.0, as it might still be years away.  8.7.0a1 was 4 years ago.  8.6.0 spent 5 years in beta.  https://sourceforge.net/projects/tcl/files/Tcl/.
I'd like to see improved tkinter docs within a year.

I don't think that license should be an issue.  Tkinter, as well as our distribution of tcl/tk binaries and the Perl and Ruby tk wrappings, must be allowed by the tcl/tk license.  At least by implication, we must be allowed to document the licensed wrapper and its usage from Python.  

The tkinter-docs listing of widget options is close to what I want to see*, except that I want to separately document shared options, as in the ttk doc.  To the extent that I would prefer your versions, you have already done a big chunk of the work for that.  Did you exactly copy the tk manual wordings or rewrite in your own words?  Do you intend to contribute what you wrote?

* In particular, you added OS-specific info.  It seems to be mostly absent from *tkinter* doc and not knowing those facts has caused grief.