Update 'README.md'

README.md

@@ -1,3 +1,14 @@
 # tqdm
 
-进度条
+进度条
+
+## Usage
+
+```
+from tqdm import tqdm
+import time
+
+if __name__=='__main__':
+    for i in tqdm(range(100)):
+        time.sleep(1)
+```