[docs] Small tweaks as reported in comments

* highlight `</form>`
* use correct id in `getElementById` call
Redirect /docs to the right page

I've hit this a few times where I want to get to docs so I take whatever
my urlbar gives me and strip out the actual page so I can get to the
root, however that's a 404.

This introduces a super easy way to redirect, which could be handy in
the future as docs get rewritten.

I would much rather do this with a real htaccess file or even just
handle 404s gracefully, but that's not currently an option with GitHub
pages (since we generate our own and don't use a custom domain).
Tutorial: show how to add showdown.js
Add pagination to blog

- Add pagination
- Display full content in /blog
- Truncate Recent posts
- Add permalink that lists all the blog posts
- Add spacing and bullet around recent posts to make it more readable
Add Stack Overflow link for doc support page.
Update wording