bug#43600: 26.3; Doc string of `hi-lock-auto-select-face'

[Drew Adams]

Doc string:

 Non-nil means highlighting commands do not prompt for the face to use.
 Instead, each hi-lock command will cycle through the faces in
 `hi-lock-face-defaults'.

Not clear what "instead" refers to.  Is it instead of non-nil, i.e.,
what nil means, or is it instead of prompting?

Something like this (or more verbose) might be clearer.

 Non-nil means highlighting commands cycle through `hi-lock-face-defaults'.
 Nil means the commands prompt for the face to use.

In GNU Emacs 26.3 (build 1, x86_64-w64-mingw32)
 of 2019-08-29
Repository revision: 96dd0196c28bc36779584e47fffcca433c9309cd
Windowing system distributor `Microsoft Corp.', version 10.0.18362
Configured using:
 `configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static -g3''