Rethink documentation sets structure

We currently have the following documentation sets/structure:

• Eclipse ESCET documentation
  • Chi documentation
  • CIF documentation
  • SeText documentation
  • ToolDef documentation

The Eclipse ESCET documentation includes the project documentation, developer documentation and documentation about the common parts/folder.

We may want to restructure it. Let's discuss here how to improve it, and what we want.

Note that this issue is about the documentation sets that are distinguishable by end users. It is not about where the sources of the documentation sets are put in the Git repository, and whether these should be all together or spread out, as that is part of #102 (closed).