fix: add missing fallbackType option in i18n middleware() (#14084)

Co-authored-by: Yan <61414485+yanthomasdev@users.noreply.github.com>

Author: ArmandPhilippot

src/content/docs/en/guides/internationalization.mdx

@@ -212,35 +212,35 @@ export const onRequest = defineMiddleware(async (ctx, next) => {
 
 #### middleware function
 
-The [`middleware`](#middleware-function) function manually creates Astro's i18n middleware. This allows you to extend Astro's i18n routing instead of completely replacing it. 
+The [`middleware()`](/en/reference/modules/astro-i18n/#middleware) function manually creates Astro's i18n middleware. This allows you to extend Astro's i18n routing instead of completely replacing it. 
 
-You can run `middleware` with [routing options](#routing) in combination with your own middleware, using the [`sequence`](/en/reference/modules/astro-middleware/#sequence) utility to determine the order:
+You can run `middleware()` with [routing options](#routing) in combination with your own middleware, using the [`sequence()`](/en/reference/modules/astro-middleware/#sequence) utility to determine the order:
 
 ```js title="src/middleware.js"
-import {defineMiddleware, sequence} from "astro:middleware";
+import { defineMiddleware, sequence } from "astro:middleware";
 import { middleware } from "astro:i18n"; // Astro's own i18n routing config
 
 export const userMiddleware = defineMiddleware(async (ctx, next) => {
   // this response might come from Astro's i18n middleware, and it might return a 404
   const response = await next();
   // the /about page is an exception and we want to render it
-  if (ctx.url.startsWith("/about")) {
+  if (ctx.url.pathname.startsWith("/about")) {
     return new Response("About page", {
-      status: 200
+      status: 200,
     });
   } else {
     return response;
   }
 });
 
-
 export const onRequest = sequence(
   userMiddleware,
   middleware({
     redirectToDefaultLocale: false,
-    prefixDefaultLocale: true
-  })
-)
+    prefixDefaultLocale: true,
+    fallbackType: "redirect",
+  }),
+);
 ```
 
 ## `domains`

src/content/docs/en/reference/modules/astro-i18n.mdx

@@ -285,7 +285,7 @@ export const onRequest = defineMiddleware((context, next) => {
 
 <p>
 
-**Type:** `(options: { prefixDefaultLocale: boolean, redirectToDefaultLocale: boolean }) => MiddlewareHandler`<br />
+**Type:** `(options: { fallbackType: "redirect" | "rewrite", prefixDefaultLocale: boolean, redirectToDefaultLocale: boolean }) => MiddlewareHandler`<br />
 <Since v="4.6.0" />
 </p>
 
@@ -310,10 +310,14 @@ const customLogic = defineMiddleware(async (context, next) => {
   return response;
 });
 
-export const onRequest = sequence(customLogic, middleware({
-	prefixDefaultLocale: true,
-	redirectToDefaultLocale: false
-}))
+export const onRequest = sequence(
+  customLogic,
+  middleware({
+    prefixDefaultLocale: true,
+    redirectToDefaultLocale: false,
+    fallbackType: "redirect",
+  }),
+);
 ```
 
 ### `requestHasLocale()`