Properly update the Uart config in examples

[SergioGasquez]

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Submission Checklist 📝

• I have updated existing examples or added new ones (if applicable).
• I have used cargo xtask fmt-packages command to ensure that all changed code is formatted correctly.
• My changes were added to the CHANGELOG.md in the proper section.
• My changes are in accordance to the esp-rs API guidelines

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• I have read the CONTRIBUTING.md guide and followed its instructions.

Pull Request Details 📖

Description

• rx_fifo_full_threshold returns a Config with the updated value, and it was not being stored, so we were using default values.
• rx_timeout is now an option in the Config struct, see UART AT character detection not working. #1700 (comment)

Testing

Tested the examples

[bjoernQ]

Thanks - that was a source of confusion

[MabezDev]

Thanks!