Improve the `help()` of type alias objects

Feature or enhancement

EDIT: See https://discuss.python.org/t/runtime-docstrings-for-type-aliases/108901

Proposal:

Consider recording __doc__ on type alias objects.

For instance:

type Pair[T] = tuple[T, T]
"""A pair of values of the same type."""

Now Pair.__doc__ is "A pair of values of the same type.".

Use it in the REPL:

>>> from mymodule import Pair
>>> help(Pair)
Help on type alias Pair in module mymodule:

Pair[T] = tuple[T, T]
 |  A pair of values of the same type.
 |
 |  Attributes:
 |
 |  __value__
 |      Lazily evaluated value of the type alias.
 |
 |  evaluate_value
 |      Evaluation function for __value__.
 |
 |  __type_params__
 |      Type parameters declared by the type alias.
 |
 |  __parameters__
 |      Type parameters after expansion.
 |
 |  __name__
 |      Name of the type alias.
 |
 |  __qualname__
 |      Qualified name of the type alias.
 |
 |  __module__
 |      Module in which the type alias was defined.

(I wrote this text by hand, the actual thing could probably be improved.)
I assume IDEs/LSPs already catch it, so this is mainly a runtime feature.

Current help() just shows a slightly confusing help on the type alias type itself:

>>> type x = int
>>> help(x)
Help on TypeAliasType in module __main__ object:

x = class TypeAliasType(builtins.object)
 |  Type alias.
 |
 |  Type aliases are created through the type statement::
 |
...

It is confusing because (1) it reads like TypeAliasType was defined in __main__ (Help on TypeAliasType in module __main__ object), and (2) almost like if i did x = typing.TypeAliasType. (Which could be improved on its own? We could instead say x = instance of class ..., not just x = class ...)

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Commencez par reproduire la sortie actuelle de help(x) pour un alias de type dans la REPL, puis suivez le traitement des objets alias de type par help() ainsi que l’implémentation des alias de type à l’exécution. Le travail est terminé lorsque les chaînes de documentation à l’exécution peuvent être enregistrées et que help(Pair) présente l’alias, sa documentation et les attributs pertinents sans décrire de manière trompeuse l’alias comme étant la classe TypeAliasType.