if REGEXP matches the headline's TITLE-OR-DESCRIPTION.
If, for example, `newsticker-auto-mark-filter-list' looks like
- \((slashdot ('old 'title \"^Forget me!$\") ('immortal 'title \"Read me\")
- \('immortal 'all \"important\"))))
+ \((slashdot (\\='old \\='title \"^Forget me!$\") (\\='immortal \\='title \"Read me\")
+ \(\\='immortal \\='all \"important\"))))
then all articles from slashdot are marked as old if they have
the title \"Forget me!\". All articles with a title containing