Todo for tutorials

[thofma]

• move tutorials out of docs (but don't enable coverage for it)
• document how to add a tutorial
• put metadata in the tutorial source file and use it to create the table
• document the pipeline
• fix the absolute links (at the moment it is hardcoded to /dev
• make it open'able in colab (requires deploying to a github repo, maybe use HeckeTutorials.jl?)