; Improve doc string of 'glyphless-char-display-control'

* lisp/international/characters.el
(glyphless-char-display-control): Doc fix.

lisp/international/characters.el

@@ -1594,12 +1594,14 @@ GROUP must be one of these symbols:
                     such as U+200C (ZWNJ), U+200E (LRM), but
                     excluding characters that have graphic images,
                     such as U+00AD (SHY).
-  `variation-selectors': U+FE00..U+FE0F, used for choosing between
-                         glyph variations (e.g. Emoji vs Text
-                         presentation).
-  `no-font':        characters for which no suitable font is found.
-                    For character terminals, characters that cannot
-                    be encoded by `terminal-coding-system'.
+  `variation-selectors':
+                    Characters in the range U+FE00..U+FE0F, used for
+                    selecting alternate glyph presentations, such as
+                    Emoji vs Text presentation, of the preceding
+                    character(s).
+  `no-font':        For GUI frames, characters for which no suitable
+                    font is found; for text-mode frames, characters
+                    that cannot be encoded by `terminal-coding-system'.
 
 METHOD must be one of these symbols:
   `zero-width': don't display.