Mediawiki Extension Mermaid

As of 2021-11 we are using Mediawiki Extension Flex Diagrams instead, since it includes the newest Mermaid version.

Extension to generate graphs by code.

• https://www.mediawiki.org/wiki/Extension:Mermaid
• https://github.com/SemanticMediaWiki/Mermaid/blob/master/README.md