Can‘t refer example file in `UserDefinedLogicalNodeCore` doc

[zhuliquan]

Describe the bug

There is minor bug which can't refer example file (i.e. user_defined_plan.rs) in UserDefinedLogicalNodeCore document

datafusion/datafusion/expr/src/logical_plan/extension.rs

Lines 212 to 217 in 780cccb

	/// This trait facilitates implementation of the [`UserDefinedLogicalNode`].
	///
	/// See the example in
	/// [user_defined_plan.rs](../../tests/user_defined_plan.rs) for an
	/// example of how to use this extension API.
	pub trait UserDefinedLogicalNodeCore:

In reality, ../../tests/user_defined_plan.rs doesn't exist and this file's location is datafusion\core\tests\user_defined\user_defined_plan.rs

To Reproduce

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Expected behavior

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Additional context

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