[Edit docs] Parts of "Developer Quickstart" need updating to work with Tailwind CSS v4.

[pjklein]

URL of the page to change: https://docs.stacks.co/guides-and-tutorials/hello-stacks-quickstart-tutorial

Quick fix = pin to Tailwind CSS 3.x

Change Code Setup to explicitly install Tailwind CSS 3.x. The rest of the instructions will then work correctly.

Updating Fix = revamp to work with Tailwind CSS 4.x

Tailwind CSS v4 eliminated the init script and the tailwind.config.js that it creates.

Context

I found this when

npx tailwindcss init -p

got the error mentioned in this Tailwind CSS issue: Unable to Run npx tailwindcss init -p - "Could Not Determine Executable to Run".

Tagging @kenrogers , else i'll address in a PR later.