Enhance tutorials by adding even more descriptive comments about agentmet4fof

[bangxiangyong]

I'm thinking of writing some short tutorials in the readthedocs panels, examples such as :

• https://gpytorch.readthedocs.io/en/latest/
• https://osbrain.readthedocs.io/en/stable/

Even more ambitious could be short tutorial videos (1-5min) can be recorded with explanations and uploaded on youtube or something.

[BjoernLudwigPTB]

So starting to work on that means as well to better structurize ReadtheDocs.org, taking https://gpytorch.readthedocs.io/en/latest/ as a best-practice example, which we could use as a template.

[BjoernLudwigPTB]

We keep tutorials and examples at one place with the code.

[BjoernLudwigPTB]

In the meantime we added quite somewhat more text and restructured the tutorials as well as better integrated them into the docs. This should be resolved by now.