René Paris authored Mar 17, 2021 and Reinhard Biegel committed Jul 08, 2021

- Migration of old documentation from markdown to restructured text
- Additional content: Installation Guide, User Guide
- Cmake build flag `WITH_DOC` for documentation (also standalone!)
- Cmake build flag `WITH_API_DOC` for former doxygen API documentation
- Cmake build target for documentation (`make doc`)

Signed-off-by: Rene <Paris&lt;rene.paris@in-tech.com>