Update repositories.txt (#6986)

Added https://github.com/dac1e/RcSwitchTransmitter

Co-authored-by: Per Tillisch <accounts@perglass.com>

Author: dac1e

repositories.txt

@@ -8433,4 +8433,5 @@ https://github.com/junzzhu/esp-mqtt-arduino
 https://github.com/skr-electronics-lab/OLEDKeyboard.git
 https://github.com/valeriofantozzi/TraccarClient.git
 https://github.com/SofaPirate/PqLEDStrip
+https://github.com/dac1e/RcSwitchTransmitter
 https://github.com/nonpawite/bcc-esp-dev