Upgrade Sphinx

1.2b2 is quite old.
Add stories and roadmap
Move existing content and add new material

Based on the user needs for the documentation, add material and
placeholders to meet those needs.
Write current roadmap
Fix removing thinking pieces from the TOC

We don’t want to link to these just yet.
Minor grammar change
Descriptive titles for each part
Minor formatting tweak
Add an about resource
Add newline to fix bold text effect
Merge pull request #19 from alphagov/roadmap

Add a roadmap