docs: rewrite index page (including dangling links to future docs)
This has been reviewed to death on the evolve-testers mailing list.
I've made some minor tweaks since the last round of reviews, but the
main content is the same.
syntax: re
/figures/[^/]+\.png$
^docs/build/
^docs/html/
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
\.err$
^tests/easy_run.sh$
^build/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$