Suggest py::smart_holder for "most situations for safety"

Author: rwgk

docs/classes.rst

@@ -42,8 +42,8 @@ constructor (see the :ref:`custom_constructors` section for details).
 .. note::
 
     Starting with pybind11v3, it is recommended to include `py::smart_holder`
-    if you plan to support conversions to C++ smart pointers. See
-    :ref:`smart_holder` for more information.
+    in most situations for safety, especially if you plan to support conversions
+    to C++ smart pointers. See :ref:`smart_holder` for more information.
 
 An interactive Python session demonstrating this example is shown below: