[BUG]: `def_property_readonly` does not include the function signature

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What version (or hash if on master) of pybind11 are you using?

v2.10.3

Problem description

When using def(...), the function signature is included in the docstring. When using def_property_readonly the function signature is not included in the docstring.

To make a simple example, I modified the cmake_example project, editing main.cpp to contain:

#include <pybind11/pybind11.h>

struct Foo {
    int do_something() const { return 5; }
};

namespace py = pybind11;

PYBIND11_MODULE(cmake_example, m) {
    py::class_<Foo>(m, "Foo")
        .def("do_something", &Foo::do_something, py::doc("Get a number"))
        .def_property_readonly("do_something_prop", &Foo::do_something, py::doc("Get a number as a property"));
}

I then compile and import the module in python:

In [1]: import cmake_example

In [2]: import inspect

In [3]: props = dict(inspect.getmembers(cmake_example.Foo))

In [4]: props['do_something'].__doc__
Out[4]: 'do_something(self: cmake_example.Foo) -> int\n\nGet a number\n'

In [5]: props['do_something_prop'].__doc__
Out[5]: 'Get a number as a property'

The expected behavior (at least according to my limited understanding) would be that do_something_prop has a docstring like do_something, including the signature with type annotations.

Is this a bug in pybind11, or a limitation of python properties?

Reproducible example code

No response

Is this a regression? Put the last known working version here if it is.

Not a regression

Start with the modified cmake_example/main.cpp example and compare the doc values for def() and def_property_readonly() using Python's inspect.getmembers. Trace the pybind11 binding entry point for def_property_readonly and its generated documentation, then add coverage for the expected signature-bearing docstring and verify the property output matches the requested behavior.