bug#31858: 27.0; doc of `window-toggle-side-windows'

[Drew Adams]

AFAICT, neither the doc string nor the manual says what toggling the
side windows DOES or MEANS.  Just what behavior or appearance is
toggled?  What happens when a side window is - or all side windows are -
toggled?

The command is said to be "handy to toggle the appearance of all side
windows on a specified frame".  But I have no idea what that appearance
toggling amounts to.  Does it swap left for right windows and top for
bottom?  Does it hide/show the currently shown/hidden side windows?
Does it reverse the order?  Does it change the focus?  Just what gets
toggled?

In GNU Emacs 27.0.50 (build 3, x86_64-w64-mingw32)
 of 2018-03-21
Repository revision: e70d0c9e66d7a8609450b2889869d16aeb0363b5
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install -C 'CFLAGS=-O2 -static -g3''