Hello,
the last sentence in the intro to the Tcl 8.6. Tutorial at
https://nikit.tcl-lang.org/page/Tcl+Tutorial+Index
reads:
Of course, we also welcome comments and suggestions about how it could
be improved - or if it's great the way it is, we don't mind a bit of
thanks, either!
But the document doesn't provide any address to which those comments,
suggestions and thanks may be sent.
Also, of the two links provided in the Credits section, one is dead and
the other one causes an access permission error on the destination server.
Best
Michael