Create index page for design proposals

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Move design_docs HTML to a template

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Link design docs index in nav bar

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Move existing design docs under new index

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Change YAML for design docs

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Syntax highlight the YAML in the README

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Add instructions for contributing design proposals

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Labels can be empty, they're handled by the :empty selector

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Use colour-coded labels in design docs index

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Merge pull request #24 from simonjbeaumont/design-docs

A new home for design proposals