fix: Move code to file

Author: neznaika0

user_guide_src/source/incoming/content_negotiation.rst

@@ -123,22 +123,13 @@ that the strict comparison will be made in the first place.
 
     Now let's consider the below example. The browser's preferred language will be set as this::
 
-    GET /foo HTTP/1.1
-    Accept-Language: fr; q=1.0, en-GB; q=0.5
+        GET /foo HTTP/1.1
+        Accept-Language: fr; q=1.0, en-GB; q=0.5
 
 In this example, the browser would prefer French, with a second choice of English (United Kingdom). Your website on another hand will
 supports German and English (United States):
 
-.. code-block:: php
-
-    $supported = [
-        'de',
-        'en-US',
-    ];
-
-    $lang = $request->negotiate('language', $supported);
-    // or
-    $lang = $negotiate->language($supported);
+.. literalinclude:: content_negotiation/008.php
 
 In this example, 'en-US' would be returned as the current language. If no match is found, it will return the first element
 in the ``$supported`` array. Here is how exactly the locale selection process works.

user_guide_src/source/incoming/content_negotiation/008.php

@@ -0,0 +1,10 @@
+<?php
+
+$supported = [
+    'de',
+    'en-US',
+];
+
+$lang = $request->negotiate('language', $supported);
+// or
+$lang = $negotiate->language($supported);