[Bf-docboard] costum toctree 2

[Tobias Heinke]

Hello everybody,

Looking at some docs 
(https://docs.newrelic.com/docs/data-analysis/user-interface-functions)
I got "inspired" to a second attempted to make the index pages look nicer.

To get rid of the list dots and add some horizontal lines instead.

https://developer.blender.org/D2472 (more detail and screenshot)

Still open are the general design decisions that probably are personal 
preference:

Differentiation of the level: currently font size, alternative: bold 
like the sidebar.
Hover: like the list dot - triangle, alternative: bold, underlined, color.

     .rst-content .toctree-wrapper li a:hover {
         font-weight: bold;
     }

No live demo, sorry.

This time no new browser tech (flex box), so no testing needed (yolo ;).
Of cause  I'm open for feedback and suggestion.

Regards,
Tobias