[Docs] Add example image download step to Image-To-Video examples (#1258)

Signed-off-by: lishunyang <lishunyang12@163.com>

docs/user_guide/examples/offline_inference/image_to_video.md

@@ -7,12 +7,19 @@ This example demonstrates how to generate videos from images using Wan2.2 Image-
 
 ## Local CLI Usage
 
+Download the example image:
+
+```bash
+wget https://vllm-public-assets.s3.us-west-2.amazonaws.com/vision_model_images/cherry_blossom.jpg
+```
+
 ### Wan2.2-I2V-A14B-Diffusers (MoE)
+
 ```bash
 python image_to_video.py \
   --model Wan-AI/Wan2.2-I2V-A14B-Diffusers \
-  --image input.png \
-  --prompt "A cat playing with yarn, smooth motion" \
+  --image cherry_blossom.jpg \
+  --prompt "Cherry blossoms swaying gently in the breeze, petals falling, smooth motion" \
   --negative_prompt "<optional quality filter>" \
   --height 480 \
   --width 832 \
@@ -27,11 +34,12 @@ python image_to_video.py \
 ```
 
 ### Wan2.2-TI2V-5B-Diffusers (Unified)
+
 ```bash
 python image_to_video.py \
   --model Wan-AI/Wan2.2-TI2V-5B-Diffusers \
-  --image input.png \
-  --prompt "A cat playing with yarn, smooth motion" \
+  --image cherry_blossom.jpg \
+  --prompt "Cherry blossoms swaying gently in the breeze, petals falling, smooth motion" \
   --negative_prompt "<optional quality filter>" \
   --height 480 \
   --width 832 \