bug#11059: 24.0.94; Please add `face-spec-set' to the elisp manual

[Drew Adams]

> > If you want your changes to play nicely with the Custom 
> > interface, you should use `custom-set-faces'.
> 
> Indeed, but this has some downsides: Custom may decide to rewrite your
> handwritten custom-set-faces.  We should document an Elisp way to
> configure faces, and I'd recommend a new function `custom-set-face'
> which works just like custom-set-faces except it applies to a single
> face and will be left alone by Custom.

Haven't thought about it much, but that sounds good to me too.

In addition, a user can try to make sure that s?he evaluates any hand-crafted
`custom-set-faces' sexp outside of the init file and `custom-file', and after
those are loaded.

I also agree that whatever is implemented and recommended in this regard, it be
documented in the Emacs manual.

But I do think it is good to recommend using Customize first and foremost.
There are lots of questions that come up (e.g. on help-gnu-emacs) because users
make mistakes when hand-coding or they do not take into account other Customize
treatments such as :set.