Update 'CARDPUTER CircuitPython/sdcard_test.py'

CARDPUTER CircuitPython/sdcard_test.py

 
 print(SD_status)
 
-# Then, reading/writing to files is as trivial as regular Python:
+# Use os to scan the SD card
+files = os.listdir("/sd")
+for file in files:
+  print(file)
+  
+print("========")
 
+# Then, reading/writing to files is as trivial as regular Python:
 with open("/sd/data.txt") as f:
     lines = f.readlines()
 for line in lines: