The "Creating a terminal application" links to https://www.erlang.org/doc/apps/stdlib/assets/tic-tac-toe.es, which has a problem.
The board characters served up the browser seem strangely encoded.

But when I use curl/wget it is encoded correctly.
I'll be looking where to report this correctly, but for now I'll report it here in case anyone trips over it.
Originally posted by @wmealing in erlang/otp#8962 (comment)
I think that this is a content encoding issue on the server.