docs: fix LSTM example import in rnn.LSTMModule

[arvindcr4]

This PR fixes a minor import issue in the LSTMModule docstring example.

• Add to the import alongside so the snippet runs as-is without raising a .

Documentation-only change.

Closes #3119

[pytorch-bot]

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[Copilot]

Pull Request Overview

This PR fixes a missing import in the LSTM example docstring to ensure the code snippet runs without errors.

• Add LSTMModule to the import statement alongside MLP in the docstring example

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