Including the following that has come up several times recent:
- How to use codegen for headers (that each target that uses the header
needs the object in it's sources)
- Using custom_targets with multiple outputs
This is a cosmetic change because github seems to interpret those
correctly. Nonetheless, it adds unnecessary noise and makes people
modifying the pages think it might be needed.
See syntax guide at https://guides.github.com/features/mastering-markdown/
This allows us to more easily have the documentation in sync with
the source code as people will have to document new features etc
right at the time where they implement it.