fix: typo in readme

Signed-off-by: Raimund Schlüßler <raimund.schluessler+github@mailbox.org>

README.md

@@ -36,7 +36,7 @@ You can also modify the configuration, for example if you want to set an include
 
 ```js
 import { createAppConfig } from '@nextcloud/vite-config'
-import { mergeConfig } from 'vite'
+import { defineConfig } from 'vite'
 import path from 'node:path'
 
 const yourOverrides = defineConfig({
@@ -89,4 +89,4 @@ For apps any styles can be injected in the JS by dynamically inject the styles i
 But this only works in DOM environments, so for libraries this might not work (e.g. while testing in the Node environment).
 
 So for libraries the CSS will still be extracted by Vite, but the extracted CSS assets will be imported.
-This way the library user can decide how to handle the imported CSS without relying on a DOM environment.
+This way the library user can decide how to handle the imported CSS without relying on a DOM environment.