docs(api): add defineNuxtRouteMiddleware util

docs/content/3.api/3.utils/define-nuxt-route-middleware.md

@@ -1,7 +1,57 @@
 # `defineNuxtRouteMiddleware`
 
-::ReadMore{link="/guide/features/routing"}
-::
+You can create named route middleware using `defineNuxtRouteMiddleware`  helper function.
+
+Route middleware are generally stored in the `middleware/` directory unless otherwise customized using [nuxt.config](/api/configuration/nuxt.config#middleware).
+
+## Usage
+
+```ts
+export default defineNuxtRouteMiddleware((middleware: RouteMiddleware) => {})
+```
+
+### Parameters
+
+`defineNuxtRouteMiddleware` provides parameter of type `RouteMiddleware` which includes two Vue route objects:
+
+- **to:** `type: RouteMiddleware` - `to` is the first argument that return the next route
+
+- **from:** `type: RouteMiddleware` - `from` is the second argument that returns the current route
+
+Learn more about available properties of **[route objects](https://v3.nuxtjs.org/api/composables/use-route)** .
 
-::NeedContribution
+## Examples
+
+### Show error page
+
+You can use route middleware to throw errors and show helpful error messages.
+
+```ts [middleware/error.ts]
+export default defineNuxtRouteMiddleware((to) => {
+  if (to.params.id === '1') {
+    showError({ statusCode: 404, statusMessage: "Page Not Found" })
+  }
+})
+```
+
+Above route middleware will take user on a custom error page defined at `~/error.vue` and show error message and code as passed from the middleware.
+
+### Redirection
+
+The route middleware below shows how you can use `useState` in combination with `navigateTo` helper method to redirect users on different routes based on their authentication status.
+
+```ts [middleware/auth.ts]
+export default defineNuxtRouteMiddleware((to, from) => {
+  const auth = useState('auth')
+
+  if (!auth.value.authenticated) {
+    return navigateTo('/login')
+  }
+  return navigateTo('/dashboard')
+})
+```
+
+Both [navigateTo](/api/utils/navigate-to) and [abortNavigation](/api/utils/abort-navigation) are globally available helper methods that you can use inside `defineNuxtRouteMiddleware` helper function.
+
+::ReadMore{link="/guide/features/routing"}
 ::