[FrameworkBundle][HttpKernel] Document collect_parameter

Author: SzymonKaminski

reference/configuration/framework.rst

@@ -1298,6 +1298,19 @@ activate the data collectors manually::
 
     $profiler->enable();
 
+collect_parameter
+.................
+
+**type**: ``string`` **default**: ``null``
+
+This option allows to enable or disable the profiler on a per request basis
+using a query parameter, body parameter or a request attribute with the given name.
+If ``collect`` flag is set to ``true``, but the parameter exists in a request
+and has any value other than ``true``, ``yes``, ``on`` or ``1``,
+the request data will not be collected.
+If ``collect`` flag is set to ``false``, but the parameter exists in a request
+and has value of ``true``, ``yes``, ``on`` or ``1``, the request data will be collected.
+
 only_exceptions
 ...............