Fix example ReadWrite

[idealsmurffittrainer]

I think there is i some mistake in exaple ReadWrite. In code below is pointless while loop which burdens CPU. I'll change if for while and "while(1);" remove
if (!SD.begin(4)) { Serial.println("initialization failed!"); while (1); }

[Deepak Khatri]

I agree with you, we should at least change the error message with something as I proposed in #73

[per1234]

Thanks for taking the time to submit an issue @idealsmurffittrainer.
This perpetual loop is intentional. Continuing with the sketch would be pointless and confusing to the user after the SD card initialization failed.