Migrating to Tcl/Tk 8.6

I have a set of developers looking for a TclX version to work with Tcl/Tk 8.6.
I understand that that TclX is no longer supported. Can someone provide pointers to any resources for converting TclX code to Tcl/Tk 8.6?
RHEL 8 documentations seems to indicate that there is an item with title above, but I seem to be having issues locating that document.

Thanks!