Move licenses of technical files and docs into REUSE.toml (!102)

## What is the bug
Gather licenses of technical files and docs into REUSE.toml. This prevents licenses from getting into the commit with the MR templates.
## How do you fix it
Add `REUSE.toml` and remove license texts

Approved-by: Jonas Jucker <jonas.jucker@env.ethz.ch>
Merged-by: Yen-Chen Chen <yen-chen.chen@kit.edu>
Changelog: bugfix