Vite tooling hint for addons

[efc]

I have twice missed the very valuable information in the Vite Tooling documentation because I was so focused on the Building an Addon document. This pull request provides a bridge that might help future me (and others like me) who are so overwhelmed with the task of building an addon with a fieldtype that they miss important information in Vite Tooling.

This also provides the syntax for building fieldtypes into addons, which does not seem to be present in the docs otherwise.

[jasonvarga]

The "CSS and JavaScript" section on the "Building an Addon" page already links to the Vite tooling page.

[efc]

Fair enough, Jason. If you all think that does the trick, I could understand that. I just know that I've missed that reference twice myself even when hunting for the solution to the "manifest not found" problem after installing a fieldtype into an addon. I just felt some focussed description of how fieldtypes are built in and the extra publish step would be helpful for others like me.