bug#34784: 26.1; Doc of pseudofunction key `<timeout>'

[Drew Adams]

See https://emacs.stackexchange.com/a/48221/105.

There is apparently a <timeout> function key and a `timeout'
function-key event?  Please consider documenting this in the Elisp
manual.


In GNU Emacs 26.1 (build 1, x86_64-w64-mingw32)
 of 2018-05-30
Repository revision: 07f8f9bc5a51f5aa94eb099f3e15fbe0c20ea1ea
Windowing system distributor `Microsoft Corp.', version 10.0.17134
Configured using:
 `configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static -g3''