doc: Create autodoc extension tutorial

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diff --git a/doc/development/tutorials/autodoc_ext.rst b/doc/development/tutorials/autodoc_ext.rst
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+Developing autodoc extension for IntEnum
+========================================
+
+The objective of this tutorial is to create an extension that adds
+support for new type for autodoc. This autodoc extension will format
+the ``IntEnum`` class from Python standard library. (module ``enum``)
+
+Overview
+--------
+
+We want the extension that will create auto-documentation for IntEnum.
+``IntEnum`` is the integer enum class from standard library ``enum`` module.
+
+Currently this class has no special auto documentation behavior.
+
+We want to add following to autodoc:
+
+* A new ``autointenum`` directive that will document the ``IntEnum`` class.
+* The generated documentation will have all the enum possible values
+  with names.
+* The ``autointenum`` directive will have an option ``:hex:`` which will
+  cause the integers be printed in hexadecimal form.
+
+
+Prerequisites
+-------------
+
+We need the same setup as in :doc:`the previous extensions <todo>`. This time,
+we will be putting out extension in a file called :file:`autodoc_intenum.py`.
+The :file:`my_enums.py` will contain the sample enums we will document.
+
+Here is an example of the folder structure you might obtain:
+
+.. code-block:: text
+
+      └── source
+          ├── _ext
+          │   └── autodoc_intenum.py
+          ├── conf.py
+          ├── index.rst
+          └── my_enums.py
+
+
+Writing the extension
+---------------------
+
+Start with ``setup`` function for the extension.
+
+.. literalinclude:: examples/autodoc_intenum.py
+   :language: python
+   :linenos:
+   :pyobject: setup
+
+
+The :meth:`~Sphinx.setup_extension` method will pull the autodoc extension
+because our new extension depends on autodoc. :meth:`~Sphinx.add_autodocumenter`
+is the method that registers our new auto documenter class.
+
+We want to import certain objects from the autodoc extension:
+
+.. literalinclude:: examples/autodoc_intenum.py
+   :language: python
+   :linenos:
+   :lines: 1-7
+
+
+There are several different documenter classes such as ``MethodDocumenter``
+or ``AttributeDocumenter`` available in the autodoc extension but
+our new class is the subclass of ``ClassDocumenter`` which a
+documenter class used by autodoc to document classes.
+
+This is the definition of our new the auto-documenter class:
+
+.. literalinclude:: examples/autodoc_intenum.py
+   :language: python
+   :linenos:
+   :pyobject: IntEnumDocumenter
+
+
+Important attributes of the new class:
+
+**objtype**
+    This attribute determines the ``auto`` directive name. In
+    this case the auto directive will be ``autointenum``.
+
+**directivetype**
+    This attribute sets the generated directive name. In
+    this example the generated directive will be ``.. :py:class::``.
+
+**priority**
+    the larger the number the higher is the priority. We want our
+    documenter be higher priority than the parent.
+
+**option_spec**
+    option specifications. We copy the parent class options and
+    add a new option *hex*.
+
+
+Overridden members:
+
+**can_document_member**
+    This member is important to override. It should
+    return *True* when the passed object can be documented by this class.
+
+**add_directive_header**
+    This method generates the directive header. We add
+    **:final:** directive option. Remember to call **super** or no directive
+    will be generated.
+
+**add_content**
+    This method generates the body of the class documentation.
+    After calling the super method we generate lines for enum description.
+
+
+Using the extension
+-------------------
+
+You can now use the new autodoc directive to document any ``IntEnum``.
+
+For example, you have the following ``IntEnum``:
+
+.. code-block:: python
+   :caption: my_enums.py
+   
+   class Colors(IntEnum):
+       """Colors enumerator"""
+       NONE = 0
+       RED = 1
+       GREEN = 2
+       BLUE = 3
+
+
+This will be the documentation file with auto-documentation directive:
+
+.. code-block:: rst
+   :caption: index.rst
+
+   .. autointenum:: my_enums.Colors
+
+
diff --git a/doc/development/tutorials/examples/autodoc_intenum.py b/doc/development/tutorials/examples/autodoc_intenum.py
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+from enum import IntEnum
+from typing import Any, Optional
+
+from docutils.statemachine import StringList
+
+from sphinx.application import Sphinx
+from sphinx.ext.autodoc import ClassDocumenter, bool_option
+
+
+class IntEnumDocumenter(ClassDocumenter):
+    objtype = 'intenum'
+    directivetype = 'class'
+    priority = 10 + ClassDocumenter.priority
+    option_spec = dict(ClassDocumenter.option_spec)
+    option_spec['hex'] = bool_option
+
+    @classmethod
+    def can_document_member(cls,
+                            member: Any, membername: str,
+                            isattr: bool, parent: Any) -> bool:
+        return isinstance(member, IntEnum)
+
+    def add_directive_header(self, sig: str) -> None:
+        super().add_directive_header(sig)
+        self.add_line('   :final:', self.get_sourcename())
+
+    def add_content(self,
+                    more_content: Optional[StringList],
+                    no_docstring: bool = False
+                    ) -> None:
+
+        super().add_content(more_content, no_docstring)
+
+        source_name = self.get_sourcename()
+        enum_object: IntEnum = self.object
+        use_hex = self.options.hex
+        self.add_line('', source_name)
+
+        for enum_value in enum_object:
+            the_value_name = enum_value.name
+            the_value_value = enum_value.value
+            if use_hex:
+                the_value_value = hex(the_value_value)
+
+            self.add_line(
+                f"**{the_value_name}**: {the_value_value}", source_name)
+            self.add_line('', source_name)
+
+
+def setup(app: Sphinx) -> None:
+    app.setup_extension('sphinx.ext.autodoc')  # Require autodoc extension
+    app.add_autodocumenter(IntEnumDocumenter)