Add new repository link for DAMM

Arduino library for calculating DAMM checksum.

Author: RobTillaart

repositories.txt

@@ -5806,6 +5806,7 @@ https://github.com/RobTillaart/DAC8560
 https://github.com/RobTillaart/DAC8571
 https://github.com/RobTillaart/DAC8574
 https://github.com/RobTillaart/DAC53001
+https://github.com/RobTillaart/DAMM
 https://github.com/RobTillaart/dateTimeHelpers
 https://github.com/RobTillaart/DCT532
 https://github.com/RobTillaart/decibel