Document how to highlight "today" in rem2html

rem2html/rem2html

@@ -96,6 +96,14 @@ Insert I<html_text> right before the E<lt>/bodyE<gt> tag.
 
 =back
 
+=head1 HIGHLIGHTING TODAY
+
+Older versions of rem2html used to highlight today's date with a red outline.
+The current version does not do that by default.  If you wish to highlight
+today's date, add the following reminder to your reminders file:
+
+    REM [realtoday()] SPECIAL HTMLCLASS rem-today
+
 =head1 AUTHOR
 
 rem2html was written by Dianne Skoll with much inspiration from an