[Library Manager] Add uMuxOutputLib to Library Manager

[Naguissa]

Hello,

Following Library Manager FAQ I open this issue to request adding uMuxOutputLib library to Arduino repository.

Repository URL is: https://github.com/Naguissa/uMuxOutputLib

It's a simple and convenient library to multiplex outputs and be able to control a lot of elements with minimum pin requirements. One example could be controlling 100 LEDs using only 20 pins.

Thanks.

[cmaglie]

done

[Naguissa]

Thanks!