Tweaks to content pages, landing page

A slew of changes that I *thought* were already merged from Tuesday's JHT.  Things like:

* Link to proper pages from the landing page
* Embed installation instructions into iframe
* Add info about countries with confirmed installs

And probably more.  These were contained in the images I emailed out to the team, and info in that email.  So will merge directly, so that @rtibbles, @jamalex, and others can use these pages to finish their content pages.