Add SHT40 repository link

[MR01Right]

This library provides an easy-to-use interface for the SHT40 digital temperature and humidity sensor from Sensirion. The SHT40 is a high-precision, low-power sensor that communicates via I2C.

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/MR01Right/SHT40:

Linting library in SHT40
WARNING: No license file found.                                                                                                                 
         See:                                                                                                                                   
         https://docs.github.com/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/licensing-a-repository
         (Rule LD002)                                                                                                                           

Linter results for project: 0 ERRORS, 1 WARNINGS

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Linting sketch in SHT40/examples/Basic

Linter results for project: no errors or warnings

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Linter results for projects: 0 ERRORS, 1 WARNINGS

[github-actions]

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