Fixed a typo in README.
Fixed a typo in README.

caamorales/ASCScreenBrightnessDetector,caamorales/ASCScreenBrightnessDetector,schneiderandre/ASCScreenBrightnessDetector,caamorales/ASCScreenBrightnessDetector,caamorales/ASCScreenBrightnessDetector,schneiderandre/ASCScreenBrightnessDetector,schneiderandre/ASCScreenBrightnessDetector