Within the old section hierarchy, all doc parts has been placed under
the introduction, e.g:
* Linux Media Infrastructure API
+ Introduction
- Video for Linux API
- Digital TV API
- ...
With separating the introduction sibling to the other parts
we get a more common section hierarchy:
* Linux Media Infrastructure API
+ Introduction
+ Video for Linux API
+ Digital TV API
+ ...
BTW: compacting the intro text.
This patch is on top of media_tree/docs-next
Signed-off-by: Markus Heiser <markus.heiser@darmarIT.de>