Updated all serial in setup examples with a note about the serial check

libraries/SD/examples/DumpFile/DumpFile.ino

@@ -32,7 +32,9 @@ void setup()
 {
  // Open serial communications and wait for port to open:
   Serial.begin(9600);
-  while(!Serial) ;
+  // this check is only needed on the Leonardo:
+  while (!Serial) ;
+ ;
 
   Serial.print("Initializing SD card...");
   // make sure that the default chip select pin is set to