(Diff Mode): Document diff-show-trailing-whitespaces.

diff --git a/doc/emacs/files.texi b/doc/emacs/files.texi
index 3ca80546a55decfe85e3ff540831fd741fd81a2a..17ed5d6d143a92b21f388ad3db97dd020597048a 100644 (file)
--- a/doc/emacs/files.texi
+++ b/doc/emacs/files.texi
@@ -2780,6 +2780,11 @@ descriptions of the changes.  @kbd{C-x 4 a} itself in Diff mode
 operates on behalf of the current hunk's file, but gets the function
 name from the patch itself.  This is useful for making log entries for
 functions that are deleted by the patch.
+
+@item M-x diff-show-trailing-whitespaces RET
+@findex diff-show-trailing-whitespaces
+Highlight syntactically problematic trailing whitespace characters
+(usually errors introduced when editing a patch).
 @end table