Docs should reference tutorials

[lgoettgens]

At least in the text block on https://docs.oscar-system.org/dev/, the existence of tutorials should be mentioned with a hyperlink to there.
Even better would be adding a "Go to Tutorials" or similar to the menu on the left-hand side.

(Just talked about this in triage)

[HereAround]

There are links to the toric geometry tutorial as well as the FTheoryTools tutorial on their individual entry pages:

• https://docs.oscar-system.org/dev/Experimental/FTheoryTools/introduction/#Tutorial
• https://docs.oscar-system.org/dev/AlgebraicGeometry/ToricVarieties/intro/#Tutorial

But certainly, one can add more links. A proposal is here:
#4480

[HereAround]

Since #4480 was merged, I will close this issue now @lgoettgens .