Improve 'describe-char-fold-equivalences' docstring

* lisp/char-fold.el (describe-char-fold-equivalences): Explain what
the output looks like.

diff --git a/lisp/char-fold.el b/lisp/char-fold.el
index eff2f5558b33b11d3cf261c581562fb9e467249b..6da2dae8471b07dc216193ce7f17a9202847b7fc 100644 (file)
--- a/lisp/char-fold.el
+++ b/lisp/char-fold.el
@@ -436,7 +436,23 @@ specify the character).  With no input, i.e. when CHAR is nil,
 describe all available character equivalences of `char-fold-to-regexp'.
 Optional argument LAX (interactively, the prefix argument), if
 non-nil, means also include partially matching ligatures and
-non-canonical equivalences."
+non-canonical equivalences.
+
+Each line of the display shows the equivalences in two different
+ways separated by a colon:
+
+    - as the literal character or sequence
+    - using an ASCII-only escape syntax
+
+For example, for the letter \\='r\\=', the first line is
+
+    r: ?\\N{LATIN SMALL LETTER R}
+
+which is for the requested character itself, and a later line has
+
+    ṟ: ?\\N{LATIN SMALL LETTER R}?\\N{COMBINING MACRON BELOW}
+
+which clearly shows what the constituent characters are."
   (interactive (list (ignore-errors
                        (read-char-by-name
                         (format-prompt "Unicode name, single char, or hex"