Update `analogReadResolution()` documentation to include UNO R4 boards

[eMUQI]

Congratulations to the Arduino team on reaching a major milestone: 200,000 units of the Arduino UNO R4 sold worldwide! This is a fantastic achievement that highlights the innovation and creativity within the Arduino community.

The UNO series is a classic and widely used tool, especially in educational settings where it serves as an essential teaching aid. As an educator working with Arduino, I have noticed that the current documentation for the analogReadResolution() function does not mention the 14-bit ADC resolution capability of the UNO R4 boards (Minima and WiFi). This allows analogRead() to return values from 0 to 16383. Including this information in the documentation will greatly benefit users.

I have submitted a pull request to address this update: PR #980. I kindly request a review of this PR.

Thank you for considering this update.