FRAME - Feedback and local tweaks from UCB run-of-show incoperated

[nuke-web3]

• (Kian) Pallet Coupling: link back to this part of their rust exam. In fact, might be good to teach them supertraits in the rust exam as well.
• Contribute diagrams for Hold and Freeze back to Substrate, akin to this.
• They are asked to implement a pretty simple StorageValue and StorageMap here, would be good to back-reference.
• Consider introducing dev_mode at the end, or as we go through, and how certain details are elided in dev_mode.
• Some names for aggregate enums is outdated, should be RuntimeCall etc. Update Enum Names in Outer Enum Talk #803
• In outer enums lecture, we cover what a cool thing type RuntimeEvet is, that you can access future types in abstract ways through traits. But we should also cover why not all pallets use them, and have to define their own RuntimeEvent, in order to add additional bounds. A similar example of this is that some pallets, despite having access to Currency or similar, need to define their own CurrencyBalance in order to fulfill types.
• in DPoS assignment template, it would be good to provide further boilerplate about how to mock find_author.
• In all assignment templates, it would be good to provide default and expected FreeId and HoldId.
• Pallet instancing, if not clearly communicated, should be mentioned at a high level with am emphasis, because it comes relevant in XCM locations.