Support functools.singledispatchmethod rendering

[9y2070m]

Problem Description

A clear and concise description of what the bug is.

Steps to reproduce the behavior:

1. minimal example

import functools
from typing import Union


class SingleDispatchMethodExample:
    """Fancy class to show the behaviour of pdoc."""
    def __init__(self):
        """The `__init__` method is empty."""

    @functools.singledispatchmethod
    def fancymethod(self, str_or_int: Union[str, int]):
        """A fancy method which is capable of handling either `str` or `int`.

        :param str_or_int: string or integr to handle
        """
        raise NotImplementedError(f"{type(str_or_int)=} not implemented!")

    @fancymethod.register
    def fancymethod_handle_str(self, str_to_handle: str):
        """Fancy method handles a string.

        :param str_to_handle: string which will be handled
        """
        print(f"{type(str_to_handle)} = '{str_to_handle}")

    @fancymethod.register
    def fancymethod_handle_int(self, int_to_handle: int):
        """Fancy method handles int.

        :param int_to_handle: int which will be handled
        """
        print(f"{type(int_to_handle)} = '{int_to_handle:x}'")

2. pdoc output shows always a copy of singledispatchmethod docstring and not the docstring from the method. (run pdoc on the example)

System Information

Paste the output of "pdoc --version" here.

pdoc: 12.0.2
Python: 3.8.10
Platform: Windows-10-10.0.19042-SP0

[9y2070m]

ideally we would like to keep the individual methods private, but still have pdoc document them

link to documentation of singledsipatchmethod https://docs.python.org/3/library/functools.html#functools.singledispatchmethod

[9y2070m]

Thanks for the fast fix 🎉