docs(tutorial): Smooth over tutorial problems, a little

[epage]

Some problems we've identified

• People are missing the cargo add -F derive on the main docs page and the footnote about using derive, so specifying cargo add -F derive in the tutorial should help draw attention to it
• People are confused by the inferred behavior from args, so prefer linking to the derive reference on the topic so people discover it sooner
• People are confused by magic vs raw attributes
  • Call this out in the "next steps" from the tutorial
  • Link out to the builder API more to help build the connection in people's minds

This is not a definitive fix but incremental improvement