i18n(ko-KR): update plugins.md (#3010)

Co-authored-by: trueberryless <99918022+trueberryless@users.noreply.github.com>

Author: jsparkdev

docs/src/content/docs/ko/reference/plugins.md

@@ -226,7 +226,7 @@ export default {
 export default {
   name: '@example/starlight-plugin',
   hooks: {
-    setup({ addRouteMiddleware }) {
+    'config:setup'({ addRouteMiddleware }) {
       addRouteMiddleware({
         entrypoint: '@example/starlight-plugin/route-middleware',
       });