📝 Update README.md with Python print buffering documentation and solutions

README.md

@@ -79,3 +79,23 @@ if __name__ == "__main__":
 ```shell
 ./show_myip.py 
 ```
+
+<br>
+
+在 Python 中，print() 函数默认会对输出进行缓存（buffering）。
+
+```python
+import time
+
+for i in range(5, 0, -1):
+    # end="" 让它不换行，flush=True 强制立即刷新缓存
+    print(f"\rcountdown: {i}", end="", flush=True)
+    time.sleep(1)
+print("\ndone！")
+```
+
+通过设置环境变量也可以禁止缓存：
+```shell
+export PYTHONUNBUFFERED=1
+```
+