docs: adopt diataxis documentation principles for user-facing tutorials and how-to guides

[hbraswelrh]

Summary

Goals

• Implement diataxis documentation style into website tutorials / how-to guides

[hbraswelrh]

Update: considering a revamp for the Gemara tutorials. A follow-up issue will be created for leveraging the diataxis principles. There should be a complete tutorial that includes usage of the gemara-publish-action and creation of an EvaluationLog. Synchronize with gemaraproj/website.