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is inserted in the buffer to describe it.
(custom-buffer-create-other-window, custom-buffer-create):
New arg DESCRIBE; pass it along.
(customize-group): Pass DESCRIBE argument.
(custom-face-menu): Improve Set and Save item strings.
(custom-group-menu): Likewise.

(custom): Don't set :button-face.
(custom-mode): Use custom-button-face here
as buffer-local value of widget-button-face.