Update DAGs in docs

[hmgaudecker]

We should get rid of the tex-pipeline.

Also, we can use the output of a template with pytask producing a DAG for some of the files (this is how, e.g., dag.png was created).

Alternatives to tex could be mermaid, or plotly (take GETTSIM stuff as a starter). The latter would be nice because of its interactive nature, but I think I remember that getting the nodes right including description etc. was not trivial.