gh-101100: Fix sphinx warnings in howto/*

[koyuki7w]

Removed sphinx roles of some classes and methods, as the classes are defined in the sample codes, not in Python.

Fixed warnings:

howto/descriptor.rst:45: WARNING: py:class reference target not found: Ten [ref.class]
howto/descriptor.rst:218: WARNING: py:class reference target not found: Person [ref.class]
howto/descriptor.rst:218: WARNING: py:class reference target not found: Person [ref.class]
howto/descriptor.rst:256: WARNING: py:class reference target not found: Person [ref.class]
howto/descriptor.rst:340: WARNING: py:class reference target not found: Validator [ref.class]
howto/descriptor.rst:363: WARNING: py:class reference target not found: Validator [ref.class]
howto/descriptor.rst:363: WARNING: py:meth reference target not found: validate [ref.meth]
howto/descriptor.rst:372: WARNING: py:class reference target not found: OneOf [ref.class]
howto/descriptor.rst:374: WARNING: py:class reference target not found: Number [ref.class]
howto/descriptor.rst:378: WARNING: py:class reference target not found: String [ref.class]
howto/descriptor.rst:876: WARNING: py:class reference target not found: Field [ref.class]
howto/descriptor.rst:1143: WARNING: py:func reference target not found: Property [ref.func]
howto/enum.rst:78: WARNING: py:class reference target not found: Weekday [ref.class]
howto/enum.rst:90: WARNING: py:class reference target not found: Weekday [ref.class]
howto/enum.rst:113: WARNING: py:class reference target not found: Weekday [ref.class]
howto/enum.rst:131: WARNING: py:class reference target not found: Weekday [ref.class]
howto/enum.rst:576: WARNING: py:class reference target not found: Animal [ref.class]
howto/enum.rst:893: WARNING: py:class reference target not found: FloatEnum [ref.class]

• Issue: Fix all Sphinx reference warnings in the documentation #101100

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📚 Documentation preview 📚: https://cpython-previews--127084.org.readthedocs.build/

[hugovk]

If we keep the class role but add an exclamation mark then we keep the formatting of a class but don't try to resolve the reference, and get no warning:

Suggested change

	The ``Ten`` class is a descriptor whose :meth:`__get__` method always
	The :class:`!Ten` class is a descriptor whose :meth:`!__get__` method always

Re: https://devguide.python.org/documentation/markup/#roles

Same applies to the others in this PR.

And we can also do it for the example __get__ method here.

[koyuki7w]

@hugovk Fixed class references by using ! prefix. __get__ is documented in https://docs.python.org/3/reference/datamodel.html#object.__get__ , so I think it is better to fix __get__ to ~object.__get__.

[hugovk]

__get__ is documented in docs.python.org/3/reference/datamodel.html#object.get , so I think it is better to fix __get__ to ~object.__get__.

Yes, good idea.

[hugovk]

Thanks!

[miss-islington-app]

Thanks @koyuki7w for the PR, and @hugovk for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12, 3.13.
🐍🍒⛏🤖

[miss-islington-app]

Sorry, @koyuki7w and @hugovk, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 733fe59206e04141fd5cf65606ebd3d42a996226 3.12

[bedevere-app]

GH-127287 is a backport of this pull request to the 3.13 branch.

[hugovk]

@koyuki7w Please could you take care of the 3.12 backport? Thanks!

[bedevere-app]

GH-127311 is a backport of this pull request to the 3.12 branch.

[koyuki7w]

@hugovk Thanks. Opened 3.12 backport PR.