* Correcting the link to docs on Just the Basics starter README
The link to documentation did not actually go to Docs. Now it does!
* fixing all other starter template READMEs with incorrect link to docs
To avoid confusion I seperated the `npm run build` and the `npm run dev` commands, beginners might get confused by each command being listed in the same list, thinking they need to run `npm run build` before Astro works properly.
Add `npm run preview` commands to all examples where they are missing
