Fix typo

Author: wkentaro

.readme/python.png

@@ -72,9 +72,12 @@ $ gdown 'https://drive.google.com/a/jsk.imi.i.u-tokyo.ac.jp/uc?id=0B_NiLAzvehC9R
 ```python
 import gdown
 
-url = 'https://drive.google.com/uc?id=0B9P1L--7Wd2vU3VUVlFnbTgtS2c'
-output = 'spam.txt'
+url = 'https://drive.google.com/uc?id=0B9P1L--7Wd2vNm9zMTJWOGxobkU'
+output = '20150428_collected_images.tgz'
 gdown.download(url, output, quiet=False)
+
+md5 = 'fa837a88f0c40c513d975104edf3da17'
+gdown.cached_download(url, output, md5=md5, postprocess=gdown.extractall)
 ```