docs: add example for accessing vite config programmatically (#18812)

Co-authored-by: Damian Głowala <48835293+DamianGlowala@users.noreply.github.com>

docs/3.api/4.advanced/2.kit.md

@@ -112,3 +112,42 @@ description: Nuxt Kit provides composable utilities to help interacting with Nux
 - `extendViteConfig(callback, options?)`
 - `addWebpackPlugin(webpackPlugin, options?)`
 - `addVitePlugin(vitePlugin, options?)`
+
+## Examples
+
+### Accessing Nuxt Vite Config
+
+If you are building an integration that needs access to the runtime Vite or webpack config that Nuxt uses, it is possible to extract this using Kit utilities.
+
+Some examples of projects doing this already:
+
+- [histoire](https://github.com/histoire-dev/histoire/blob/main/packages/histoire-plugin-nuxt/src/index.ts)
+- [nuxt-vitest](https://github.com/danielroe/nuxt-vitest/blob/main/packages/nuxt-vitest/src/config.ts)
+- [@storybook-vue/nuxt](https://github.com/storybook-vue/nuxt/blob/main/src/preset.ts)
+
+Here is a brief example of how you might access the Vite config from a project; you could implement a similar approach to get the webpack configuration.
+
+```js
+import { loadNuxt, buildNuxt } from '@nuxt/kit'
+
+// https://github.com/nuxt/nuxt/issues/14534
+async function getViteConfig() {
+  const nuxt = await loadNuxt({ cwd: process.cwd(), dev: false, overrides: { ssr: false } })
+  return new Promise((resolve, reject) => {
+    nuxt.hook('vite:extendConfig', (config, { isClient }) => {
+      if (isClient) {
+        resolve(config)
+        throw new Error('_stop_')
+      }
+    })
+    buildNuxt(nuxt).catch((err) => {
+      if (!err.toString().includes('_stop_')) {
+        reject(err)
+      }
+    })
+  }).finally(() => nuxt.close())
+}
+
+const viteConfig = await getViteConfig()
+console.log(viteConfig)
+```