Log when exiting due to stdin being closed on watch

[oliverpool]

Wish: add a log line when tailwindcss --watch exists because stdin was closed, with an hint regarding --watch=always, like:

console.log("stdin was closed, exiting tailwind (set --watch=always to keep running instead)")

Rationale

Currently tailwindcss --watch exits if stdin gets closed:

tailwindcss/packages/@tailwindcss-cli/src/commands/build/index.ts

Lines 264 to 266 in 8c6c291

	// Abort the watcher if `stdin` is closed to avoid zombie processes. You can
	// disable this behavior with `--watch=always`.
	if (args['--watch'] !== 'always') {

I have a Makefile where multiple targets are started in paralell:

dev: 
	# start all targets in parallel
	@$(MAKE) -j2 dev-server dev-tailwind

dev-server:
	# runs the server

dev-tailwind: 
	npm run dev:tailwind-watch

If dev-tailwind is after dev-server, then it gets a closed stdin (and tailwind exits immediately without error).
If dev-tailwind is before dev-server, then it gets the stdin from my terminal and everything works.

It took me a while to understand this. And another while discover the --watch=always possibility.
Having such a log line would have spared me quite some time (inverting the default behavior would be even better for my usecase, however it would be a breaking change).