New library addition. (#6890)

* Update repositories.txt

* Update repositories.txt

Author: littlemanbuilds

repositories.txt

@@ -24,6 +24,7 @@ https://github.com/PTSolns/BMx280
 https://github.com/Pallob-Gain/packet_device
 https://github.com/gavinlyonsrepo/display16_LTSM
 https://github.com/littlemanbuilds/ESP32_MCPWM
+https://github.com/littlemanbuilds/Universal_Button
 https://github.com/gavinlyonsrepo/ST7735_LTSM
 https://github.com/anaveo/ParkingSensor
 https://github.com/m5stack/M5SwitchC6-ESP-NOW