Doc fixes for
defface and friends.
* lisp/cus-edit.el (custom-unlispify-remove-prefixes): Add warning.
* lisp/custom.el (
defface): Doc fix.
* doc/lispref/customize.texi (Customization): Define customization more
carefully.
(Common Keywords): Add xref to Constant Variables.
* doc/lispref/display.texi (Faces): Discuss anonymous faces.
(Face Attributes): Tweak intro.
(Defining Faces): Move after the Face Attributes node. Copyedits.
(Displaying Faces): Describe role of inheritance.
* doc/lispref/variables.texi (Defining Variables): Link to defcustom's node
instead of the higher-level Customization chapter.
Fixes: debbugs:11440