Improve document structure

Since the start of this working group the TR has rather increased in size. Working with it could be easier if we split the document up into several chapters which are simply embedded in one main file.

added feature request label

assigned to @mrodzis

mentioned in merge request !26 (merged)

created merge request !26 (merged) to address this issue

mentioned in commit d2acdbf1

closed via merge request !26 (merged)

mentioned in commit 4d1b1edb

mentioned in commit aca4c11e