Update repositories.txt

Author: abcdaaaaaaaaa

repositories.txt

@@ -603,6 +603,7 @@ https://github.com/Aasim-A/AsyncTimer
 https://github.com/abaskin/MAX72XX
 https://github.com/abcdaaaaaaaaa/MQSpaceData.h
 https://github.com/abcdaaaaaaaaa/RadioactiveDataScience
+https://github.com/abcdaaaaaaaaa/MG811DataScience
 https://github.com/abderraouf-adjal/ArduinoSpritzCipher
 https://github.com/abderraouf-adjal/Embedded-PID
 https://github.com/AbdoullahBougataya/QCFA