Add todo note

iot/main/storage.cpp

@@ -8,7 +8,10 @@ SdFat* card = NULL;
 
 void store_reading(uint32_t id, GPSLocation location) {
 	SdFat card;
-	card.begin()
+	card.begin(PIN_SPI_CS_SD);
+	
+	// Port the rest of this to SdFat from SD
+	
 	// Open the file to  write the data to. If it doesn't exist it will be created.
 	// Unlike elsewhere, FILE_WRITE opens the file with the cursor starting at the end, so it's basically actually equivalent to FILE_APPEND that we use in other environments. Confusing, I know.
 	File handle = SD.open(SD_FILENAME, FILE_WRITE);