bug#33553: Document negatively listing fonts for character range

[積丹尼 Dan Jacobson]

>>>>> "rr" == Richard Stallman <rms@gnu.org> writes:

>> > + Prohibit a certain font for a certain range of characters

>> That's because there is no way.  You must instead use another font for
>> that range of characters.

rr> Is there a null font, that one could specify for that range of characters
rr> and thus prevent use of any other font?

All I know is often a user is trying to communicate through their .emacs that
they don't want to use a certain font for a certain range(s) of
characters, so please give them the power to do that.

Don't force them to have to specify what other font should be used,
and don't force them to ban that whole font completely.

I had to say
      (set-fontset-font "fontset-default" #x20AC "AR PL UKai TW MBE"); To see 
EURO SIGN "€"
because
      (add-to-list 'face-ignored-fonts "eten-fixed-medium-r-normal");  Wrecks 
Chinese
was serious overkill, in
https://www.jidanni.org/comp/configuration/.emacs