Fixing example code

Author: colevscode

docs/tokens_in_cookies.rst

@@ -97,7 +97,7 @@ Then extract the CSRF token from the cookie and pass it to the server via a hidd
 
   <form id="my_form" method="POST">
     ...
-    <input id="csrf_input" type="hidden">
+    <input id="csrf_input" name="csrf_token" type="hidden">
     <button>Submit</button>
   </form>