Fix inconsistent locals usage in middleware code examples (#14106)

Co-authored-by: Armand Philippot <git@armand.philippot.eu>

Author: morinokami

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

@@ -23,6 +23,7 @@ Middleware also allows you to set and share request-specific information across
         // intercept data from a request
         // optionally, modify the properties in `locals`
         context.locals.title = "New title";
+        context.locals.property = "information";
 
         // return a Response or the result of calling `next()`
         return next();
@@ -62,10 +63,12 @@ You can store any type of data inside `locals`: strings, numbers, and even compl
 export function onRequest (context, next) {
     // intercept data from a request
     // optionally, modify the properties in `locals`
-    context.locals.user.name = "John Wick";
+    context.locals.user = { id: 1, name: "John Wick" };
     context.locals.welcomeTitle = () => {
-        return "Welcome back " + locals.user.name;
+        return "Welcome back " + context.locals.user.name;
     };
+    context.locals.orders = new Map([["1", { product: "socks" }]]);
+    context.locals.property = "information";
 
     // return a Response or the result of calling `next()`
     return next();