Add content format as an enumeration.

Signed-off-by: Chris Lamb <chris@chris-lamb.co.uk>
Match the template at least.

Signed-off-by: Chris Lamb <chris@chris-lamb.co.uk>
Add switch.

Signed-off-by: Chris Lamb <chris@chris-lamb.co.uk>
Given that we run it through |safe, don't take any chances.

Signed-off-by: Chris Lamb <chris@chris-lamb.co.uk>
Support restructuredtext

Signed-off-by: Chris Lamb <chris@chris-lamb.co.uk>