Update and improve Blob SvelteKit example (#847)

### Description

- update to latest version of Svelte(Kit)
- use static environment variable feature for better local development
experience
- use adapter-vercel
- improve readme

### Demo URL

https://blob-sveltekit-lake.vercel.app/

### Type of Change

- [ ] New Example
- [x] Example updates (Bug fixes, new features, etc.)
- [ ] Other (changes to the codebase, but not to examples)

### New Example Checklist

- [ ] 🛫 `npm run new-example` was used to create the example
- [ ] 📚 The template wasn't used but I carefuly read the [Adding a new
example](https://github.com/vercel/examples#adding-a-new-example) steps
and implemented them in the example
- [ ] 📱 Is it responsive? Are mobile and tablets considered?

storage/blob-sveltekit/.env.example

@@ -0,0 +1 @@
+BLOB_READ_WRITE_TOKEN=

storage/blob-sveltekit/README.md

@@ -27,45 +27,30 @@ You can choose from one of the following two methods to use this repository:
 
 ### One-Click Deploy
 
-Deploy the example using [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=vercel-examples):
+Deploy the example using [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=vercel-examples)
 
 [![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/clone?repository-url=https%3A%2F%2Fgithub.com%2Fvercel%2Fexamples%2Ftree%2Fmain%2Fstorage%2Fblob-sveltekit&project-name=blob-sveltekit&repository-name=blob-sveltekit&demo-title=Vercel%20Blob%20Svelte%20Starter&demo-description=Simple%20SvelteKit%20template%20that%20uses%20Vercel%20Blob%20to%20track%20pageviews.&demo-url=https%3A%2F%2Fblob-sveltekit.vercel.app%2F&demo-image=https%3A%2F%2Fblob-sveltekit.vercel.app%2Fopengraph-image.png&stores=%5B%7B"type"%3A"blob"%7D%5D)
 
-# create-svelte
+### Clone and Deploy
 
-Everything you need to build a Svelte project, powered by [`create-svelte`](https://github.com/sveltejs/kit/tree/master/packages/create-svelte).
-
-## Creating a project
-
-If you're seeing this, you've probably already done this step. Congrats!
+Execute the following command to download the example into the `my-project` folder:
 
 ```bash
-# create a new project in the current directory
-pnpm create svelte@latest
-
-# create a new project in my-app
-pnpm create svelte@latest my-app
+npx degit@latest https://github.com/vercel/examples/storage/blob-sveltekit my-project
 ```
 
-## Developing
+Once you've created the project and installed dependencies with `pnpm install`, copy the `.env.example` file in this directory to `.env.local` (which will be ignored by Git). Then open `.env.local` and set the environment variables to match the ones in your Vercel Storage Dashboard.
 
-Once you've created a project and installed dependencies with `pnpm install`, start a development server:
+Alternatively, if you have setup a project already and you have installed the Vercel CLI, you can also pull the environment variables using the following command:
 
 ```bash
-pnpm dev
-
-# or start the server and open the app in a new browser tab
-pnpm dev --open
+vercel env pull .env.local
 ```
 
-## Building
-
-To create a production version of your app:
+Next, run SvelteKit in development mode:
 
 ```bash
-pnpm build
+pnpm dev
 ```
 
-You can preview the production build with `pnpm preview`.
-
-> To deploy your app, you may need to install an [adapter](https://kit.svelte.dev/docs/adapters) for your target environment.
+Deploy it to the cloud with [Vercel](https://vercel.com/new?utm_source=github&utm_medium=readme&utm_campaign=vercel-examples) ([Documentation](https://vercel.com/docs/frameworks/sveltekit)).

storage/blob-sveltekit/package.json

@@ -13,19 +13,20 @@
     "check:watch": "svelte-kit sync && svelte-check --tsconfig ./jsconfig.json --watch"
   },
   "devDependencies": {
-    "@sveltejs/adapter-auto": "^2.0.0",
-    "@sveltejs/kit": "^1.5.0",
+    "@sveltejs/adapter-vercel": "^4.0.3",
+    "@sveltejs/kit": "^2.0.6",
+    "@sveltejs/vite-plugin-svelte": "^3.0.1",
     "autoprefixer": "^10.4.14",
     "postcss": "^8.4.23",
-    "svelte": "^3.54.0",
-    "svelte-check": "^3.0.1",
+    "svelte": "^4.2.8",
+    "svelte-check": "^3.6.2",
     "tailwindcss": "^3.3.2",
     "turbo": "^1.9.3",
-    "typescript": "^5.0.0",
-    "vite": "^4.3.0"
+    "typescript": "^5.0.4",
+    "vite": "^5.0.10"
   },
   "dependencies": {
-    "@vercel/blob": "^0.8.1",
+    "@vercel/blob": "^0.16.1",
     "dotenv-expand": "^10.0.0"
   }
 }