[tutorial] edited hands-on practices (#1899)

* Add handson to ColossalAI.

* Change names of handsons and edit sequence parallel example.

* Edit wrong folder name

* resolve conflict

* delete readme

examples/tutorial/stable_diffusion/scripts/tests/test_watermark.py

@@ -0,0 +1,18 @@
+import cv2
+import fire
+from imwatermark import WatermarkDecoder
+
+
+def testit(img_path):
+    bgr = cv2.imread(img_path)
+    decoder = WatermarkDecoder('bytes', 136)
+    watermark = decoder.decode(bgr, 'dwtDct')
+    try:
+        dec = watermark.decode('utf-8')
+    except:
+        dec = "null"
+    print(dec)
+
+
+if __name__ == "__main__":
+    fire.Fire(testit)