(newsticker--decode-iso8601-date, newsticker--set-customvar,

(newsticker--decode-iso8601-date, newsticker--set-customvar,
newsticker--buffer-insert-item, newsticker--do-run-auto-mark-filter,
newsticker--parse-generic-feed): Doc fixes.
(newsticker--retrieval-timer-list, newsticker-url-list,
newsticker-hide-immortal-items-in-echo-area,
newsticker-hide-obsolete-items-in-echo-area, newsticker-new-item-face,
newsticker--enclosure, newsticker-buffer-update,
newsticker-w3m-show-inline-images, newsticker--parse-atom-0.3,
newsticker--parse-rss-1.0, newsticker--parse-generic-feed,
newsticker--cache-contains, newsticker--stat-num-items,
newsticker-download-enclosures): Fix typos in docstrings.