Use static Request methods in Trusting Proxies doc

As these methods manipulate static properties, it makes sense to use the static methods. This also means that we don't need to create a throwaway Request instance just to set the trusted proxies.

Author: gunnarlium

components/http_foundation/trusting_proxies.rst

@@ -22,10 +22,8 @@ your proxy.
 
     use Symfony\Component\HttpFoundation\Request;
 
-    $request = Request::createFromGlobals();
-
     // only trust proxy headers coming from this IP addresses
-    $request->setTrustedProxies(array('192.0.0.1', '10.0.0.0/8'));
+    Request::setTrustedProxies(array('192.0.0.1', '10.0.0.0/8'));
 
 Configuring Header Names
 ------------------------
@@ -40,10 +38,10 @@ By default, the following proxy headers are trusted:
 If your reverse proxy uses a different header name for any of these, you
 can configure that header name via :method:`Symfony\\Component\\HttpFoundation\\Request::setTrustedHeaderName`::
 
-    $request->setTrustedHeaderName(Request::HEADER_CLIENT_IP, 'X-Proxy-For');
-    $request->setTrustedHeaderName(Request::HEADER_CLIENT_HOST, 'X-Proxy-Host');
-    $request->setTrustedHeaderName(Request::HEADER_CLIENT_PORT, 'X-Proxy-Port');
-    $request->setTrustedHeaderName(Request::HEADER_CLIENT_PROTO, 'X-Proxy-Proto');
+    Request::setTrustedHeaderName(Request::HEADER_CLIENT_IP, 'X-Proxy-For');
+    Request::setTrustedHeaderName(Request::HEADER_CLIENT_HOST, 'X-Proxy-Host');
+    Request::setTrustedHeaderName(Request::HEADER_CLIENT_PORT, 'X-Proxy-Port');
+    Request::setTrustedHeaderName(Request::HEADER_CLIENT_PROTO, 'X-Proxy-Proto');
 
 Not trusting certain Headers
 ----------------------------
@@ -53,4 +51,4 @@ listed above are trusted. If you need to trust some of these headers but
 not others, you can do that as well::
 
     // disables trusting the ``X-Forwarded-Proto`` header, the default header is used
-    $request->setTrustedHeaderName(Request::HEADER_CLIENT_PROTO, '');
+    Request::setTrustedHeaderName(Request::HEADER_CLIENT_PROTO, '');