* Move overview and introduction files into a single folder
* Remove about_this_book.md We can add a guide to contributing to documentation,
  and mention the book there.
* Remove heartbleed case study This has been a stubbed out article for ~3 years.
  We might consider an article like this for a technical white paper,
  or a blog post, if someone gets inspired.
* Stub out design/drivers and design/memory files
* Remove will redox replace linux
* Differentiate: Philosophy, Why a New OS, Goals

Refs #134