Update README.md

Fix minor bugs in usage example

README.md

@@ -56,7 +56,7 @@ from diffusers import UniDiffuserPipeline
 
 device = "cuda"
 model_id_or_path = "thu-ml/unidiffuser-v0"
-pipe = UniDiffuserPipeline.from_pretrained(model_id_or_path)
+pipe = UniDiffuserPipeline.from_pretrained(model_id_or_path, torch_dtype=torch.float16)
 pipe.to(device)
 
 # Joint image-text generation. The generation task is automatically inferred.
@@ -89,7 +89,7 @@ init_image = init_image.resize((512, 512))
 
 sample = pipe(image=init_image, num_inference_steps=20, guidance_scale=8.0)
 i2t_text = sample.text[0]
-print(text)
+print(i2t_text)
 
 # Image variation can be performed with a image-to-text generation followed by a text-to-image generation:
 sample = pipe(prompt=i2t_text, num_inference_steps=20, guidance_scale=8.0)