Clean-up `genDocs` scripts

[holzkohlengrill]

Description

Since we switched to GitHub pages there is no need for html documentation anymore.

To be discussed if we should keep the html generation part for docs. However it might likely fail at some point since it won't be executed regularly anymore.

• Tag (git) the last working state of genDocs
• Then remove this part
• Question: We could/should keep the call graph and UML part since this might still be useful (-> size would be higher in this case)