docs(aio): fix HttpClient's interceptor sample

aio/content/guide/http.md

@@ -268,12 +268,12 @@ has a single `intercept()` method. Here is a simple interceptor which does nothi
 
 ```javascript
 import {Injectable} from '@angular/core';
-import {HttpEvent, HttpInterceptor, HttpHandler, HttpRequest) from '@angular/common/http';
+import {HttpEvent, HttpInterceptor, HttpHandler, HttpRequest} from '@angular/common/http';
 
 @Injectable()
 export class NoopInterceptor implements HttpInterceptor {
   intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
-    return next.handle(Req);
+    return next.handle(req);
   }
 }
 ```