Fix the MultiSerialMega Example Schematic Image

[jglatts]

What This PR Changes

• Fixes the schematic image on the MultiSerialMega example page,
• Schematic Issue - Multiple Serial Ports on the Arduino Mega #2261

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[jglatts]

Looking more at the image, the deleted asset is using Serial0 pins which is tied to the monitor.
The other image is using Serial1 pins, which the example code needs.
However the Serial1 pins to the UART enabled device is incorrect, will close this PR for now.