Add advisory about content being out of date (sveltejs#97)

* Add advisory about content being out of date

* Remove terser from ignored files

This was throwing "Error: expected to find node_modules/vite/dist/node/terser.js" at build time

Author: geoffrich

content/tutorial/01-svelte/01-introduction/01-welcome-to-svelte/README.md

@@ -2,6 +2,8 @@
 title: Welcome to Svelte
 ---
 
+> WARNING: this content is a work in progress and may be out of date. If you are learning Svelte, please refer to the [tutorial on svelte.dev](https://svelte.dev/tutorial) for now. If you are learning SvelteKit, refer to the [SvelteKit docs](https://kit.svelte.dev/docs).
+
 Welcome to the Svelte tutorial! This will teach you everything you need to know to easily build fast, small web applications.
 
 You can also consult the [API docs](https://svelte.dev/docs) and the [examples](https://svelte.dev/examples), or — if you're impatient to start hacking on your machine locally — create a project with `npm init svelte`.

content/tutorial/02-sveltekit/01-concepts/01-introducing-sveltekit/README.md

@@ -2,6 +2,8 @@
 title: What is SvelteKit?
 ---
 
+> WARNING: this content is a work in progress and is not up to date with breaking changes in the latest version of SvelteKit. For the latest information, refer to the [SvelteKit docs](https://kit.svelte.dev/docs).
+
 So far, we've been working on individual components, or groups of components, in isolation. But to build a complete app, you need more than just components.
 
 That's where SvelteKit comes in. Whereas Svelte is a _component framework_, SvelteKit is an _app framework_ (or 'metaframework', depending on who you ask) that solves the tricky problems of building something production-ready:

scripts/create-common-bundle/index.js

@@ -20,7 +20,6 @@ const ignored_extensions = ['.d.ts', '.map', '.md'];
 const ignored_directories = ['.svelte-kit', 'node_modules/.bin', 'node_modules/rollup/dist/shared'];
 
 const ignored_files = new Set([
-	'node_modules/vite/dist/node/terser.js',
 	'node_modules/rollup/dist/es/rollup.browser.js',
 	'node_modules/rollup/dist/rollup.browser.js',
 	'node_modules/svelte/compiler.js'