Template improvements

[tg-x]

• Rename EngineFamily to EngineBehaviour
• Improve ToC structure for engines
  • Move overview to main engine page, keeping the messages separate for better structure
• Many small fixes for consistency (type names, page & section titles, etc)
• Improved juvix imports usage
• e.g. types.engines imports types.engines_* and types.anoma imports types.anoma_*, while types imports everything

[github-actions]

Success! The preview of this PR will be available at https://anoma.github.io/nspec/pr-193/.

[jonaprieto]

• Separate template messages from overview for clarity and better overview (we also had it separate before in the old specs).

While your proposal is reasonable (separate messages from the overview page), I'd pass. We had a similar organisation of the templates as you proposed at some point. We, however, wanted to include the message types right into the eye on the engine's first page, similarly, as when opening docs from API documentation. Ultimately, messages are the first entry point for interacting with the engines.

• Use Template Engine in the ToC to link to the overview, thus [[Template Engine]] wiki links lead to the right place.

Yes, this change would be good. Can we have it in another PR?

• In everything.juvix.md only import top-level modules as the rest are already imported from those modules.
• Simplify imports

I'd pass over this change. I don't expect anyone to import this module. It's for traceability. If we do as you say, the filename and everything else are meaningless.

Of course, if you intend to import definitions of an engine, your first one-go option is importing the base file, e.g., node_architecture.engines.ticker