update Svelte Setup to reflect current preferred testing framework (#1123)

Author: bertybot

docs/svelte-testing-library/intro.mdx

@@ -41,4 +41,4 @@ Introduction][dom-solution-explainer] for a more in-depth explanation.
 1.  A test runner or framework.
 2.  Specific to a testing framework.
 
-We recommend Jest as our preference.
+We recommend Vitest as our preference.

docs/svelte-testing-library/setup.mdx

@@ -4,9 +4,80 @@ title: Setup
 sidebar_label: Setup
 ---
 
-We recommend using [Jest](https://jestjs.io) but you're free to use the library
+We recommend using [Vitest](https://vitest.dev/) but you're free to use the library
 with any testing framework and runner you're comfortable with.
 
+## Vitest
+1.  Install Vitest and jsdom
+
+    ```
+    npm install --save-dev vitest jsdom
+    ```
+
+2.  Add the following to your `package.json`
+
+    ```json
+    {
+      "scripts": {
+        "test": "vitest run src",
+        "test:watch": "vitest src"
+      }
+    }
+    ```
+
+3.  You'll need to compile the Svelte components before using them in Vitest, so
+    you need to install
+    [@sveltejs/vite-plugin-svelte](https://github.com/sveltejs/vite-plugin-svelte) and Vite
+    
+
+    ```
+    npm install --save-dev @sveltejs/vite-plugin-svelte vite
+    ```
+
+4.  Add a `vitest.config.ts` configuration file to the root of your project
+
+    ```js
+    import { defineConfig } from 'vite';
+    import { svelte } from '@sveltejs/vite-plugin-svelte';
+
+    export default defineConfig({
+        plugins: [svelte({ hot: !process.env.VITEST })],
+        test: {
+            include: ['src/**/*.{test,spec}.{js,mjs,cjs,ts,mts,cts,jsx,tsx}'],
+            globals: true,
+            environment: 'jsdom'
+        }
+    });
+
+    ```
+
+5.  This is optional but it is recommended, you can install
+    [jest-dom](https://github.com/testing-library/jest-dom) to add handy
+    assertions to Jest
+
+    5.1 Install `jest-dom`
+
+    ```
+    npm install --save-dev @testing-library/jest-dom
+    ```
+
+    5.2 import `@testing-library/jest-dom` at the start of your test files
+
+    ```js
+    import '@testing-library/jest-dom';
+    ```
+
+6.  Create your component and a test file (checkout the rest of the docs to see how)
+    and run the following command to run the tests.
+
+    ```
+    npm run test
+    ```  
+### SvelteKit
+
+To use Vitest with SvelteKit install `vitest-svelte-kit`, which includes a preconfigured Vitest configuration for SvelteKit projects.
+You can take a look at the [`vitest-svelte-kit` configuration docs](https://github.com/nickbreaton/vitest-svelte-kit/tree/master/packages/vitest-svelte-kit#configuring) for further instructions.
+
 ## Jest
 
 1.  Install Jest & jest-environment-jsdom
@@ -99,79 +170,14 @@ with any testing framework and runner you're comfortable with.
     ```
     npm run test
     ```
-## Vitest
-1.  Install Vitest and jsdom
-
-    ```
-    npm install --save-dev vitest jsdom
-    ```
-
-2.  Add the following to your `package.json`
-
-    ```json
-    {
-      "scripts": {
-        "test": "vitest run src",
-        "test:watch": "vitest src"
-      }
-    }
-    ```
-
-3.  You'll need to compile the Svelte components before using them in Vitest, so
-    you need to install
-    [@sveltejs/vite-plugin-svelte](https://github.com/sveltejs/vite-plugin-svelte) and Vite
-    
-
-    ```
-    npm install --save-dev @sveltejs/vite-plugin-svelte vite
-    ```
-
-4.  Add a `vitest.config.ts` configuration file to the root of your project
-
-    ```js
-    import { defineConfig } from 'vite';
-    import { svelte } from '@sveltejs/vite-plugin-svelte';
-
-    export default defineConfig({
-        plugins: [svelte({ hot: !process.env.VITEST })],
-        test: {
-            include: ['src/**/*.{test,spec}.{js,mjs,cjs,ts,mts,cts,jsx,tsx}'],
-            globals: true,
-            environment: 'jsdom'
-        }
-    });
-
-    ```
-
-5.  This is optional but it is recommended, you can install
-    [jest-dom](https://github.com/testing-library/jest-dom) to add handy
-    assertions to Jest
-
-    5.1 Install `jest-dom`
 
-    ```
-    npm install --save-dev @testing-library/jest-dom
-    ```
-
-    5.2 import `@testing-library/jest-dom` at the start of your test files
-
-    ```js
-    import '@testing-library/jest-dom';
-    ```
-
-6.  Create your component and a test file (checkout the rest of the docs to see how)
-    and run the following command to run the tests.
-
-    ```
-    npm run test
-    ```
-## Typescript
+### Typescript
 
-To use Typescript, you'll need to install and configure `svelte-preprocess` and
+To use Typescript with Jest, you'll need to install and configure `svelte-preprocess` and
 `ts-jest`. For full instructions, see the
 [`svelte-jester`](https://github.com/mihar-22/svelte-jester#typescript) docs.
 
-## Preprocessors
+### Preprocessors
 
 If you'd like to also include any
 [Svelte preprocessors](https://github.com/sveltejs/svelte-preprocess) then