www: Ensure to include softwares recently added

www: Ensure to include softwares recently added

man pages of some GNU packages added recently (automake, bison, m4)
were not listed in the index page expectedly. New packages need to be
added to www/INDEX/{gnu,linux,misc}.list. Otherwise, such packages are
not listed in the index pages.

This commit also fixes links in the news.

* Correct a typo in a link to GNU_diffutils index.
* Use lowercase IDs for GNU make and GNU findutils.
  lowercases are used in the index page. While IDs in URLs are
  case-insensitive, it is better to use same IDs and there is
  no good reason to capitalize them.