Doc updates/indexing. doc/admin_guide.txt, doc/customizing.txt, doc/features.txt, doc/installation.txt, doc/mysql.txt, doc/postgresql.txt: adding index entries doc/customizing.txt: reference schema changes later in document in addition to wiki. website/www/contents.txt: make wiki url https:.... Remove indices/tables as they don't show up in web interface. Put docs/announcement.txt into hidden toctree to silence warning from sphinx. Announcement.txt is referenced from index.txt so can't silence by adding to conf.py exclude_patern. website/www/index.txt: mention security and other improvements in jinja2 templates. website/www/conf.py: get rid of all warning by using exclude_patterns to ignore docs that aren't included. Remove exclude_trees using exclude_pattern instead. Make html_add_permalinks value acceptable so no warning reported. website/www/_static/style.css, website/www/_templtes/layout.html: add prev/next/index links for all doc pages.

--- a/doc/features.txt	Mon May 11 11:12:25 2020 -0400
+++ b/doc/features.txt	Wed May 13 00:40:14 2020 -0400
@@ -4,7 +4,7 @@
 
 Roundup is a simple-to-use and -install issue-tracking system with
 web, e-mail and command-line interfaces. It is based on the winning design
-from Ka-Ping Yee in the Software Carpentry "Track" design competition.
+from Ka-Ping Yee in the :index:`Software Carpentry` "Track" design competition.
 
 *simple to install*
  - installation (including web interface) takes about 30 minutes