Update some modules documentation

[SergioGasquez]

Thank you for your contribution!

We appreciate the time and effort you've put into this pull request.
To help us review it efficiently, please ensure you've gone through the following checklist:

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

Extra:

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

Pull Request Details 📖

Description

Updated the module documentation of I2C, LEDC and UART. Documents how to invert signals in UART (#1216)

Testing

I've run run-doc-test of xtask

[bjoernQ]

LGTM - Thanks!

[jessebraham]

Thanks for this, looks good to me! I did just notice one small typo though, if you don't mind fixing it.