Add a deprecation notice

Author: javiereguiluz

components/var_exporter.rst

@@ -260,6 +260,11 @@ convert non-lazy classes to lazy ones::
         $instance->validateHash();
     });
 
+.. deprecated:: 7.0
+
+    The ``initializer`` function allowed passing two arguments to it to initialize
+    properties one by one. This feature was removed in Symfony 7.0.
+
 While you never query ``$processor->hash`` value, heavy methods will never be
 triggered. But still, the ``$processor`` object exists and can be used in your
 code, passed to methods, functions, etc.