adding a placeholder to chatbot

Gradio now supports adding a placeholder in your chatbot. I duplicated your demo and added a placeholder for demonstration purposes. This PR will update the Chatbot to resemble the image below:



app.py

@@ -261,6 +261,13 @@ block_css = """
 
 """
 
+placeholder = """
+<img src="https://raw.githubusercontent.com/X-PLUG/mPLUG-DocOwl/main/assets/mPLUG_new1.png" style="width:40%">
+
+**mPLUG-DocOwl1.5: Unified Stucture Learning for OCR-free Document Understanding**
+
+"""
+
 def build_demo(embed_mode):
     textbox = gr.Textbox(show_label=False, placeholder="Enter text and press ENTER", container=False)
     with gr.Blocks(title="mPLUG-Owl2", theme=gr.themes.Default(), css=block_css) as demo:
@@ -294,7 +301,7 @@ def build_demo(embed_mode):
                     max_output_tokens = gr.Slider(minimum=0, maximum=1024, value=512, step=64, interactive=True, label="Max output tokens",)
 
             with gr.Column(scale=8):
-                chatbot = gr.Chatbot(elem_id="Chatbot", label="mPLUG-DocOwl1.5 Chatbot", height=600)
+                chatbot = gr.Chatbot(elem_id="Chatbot", label="mPLUG-DocOwl1.5 Chatbot", height=600, placeholder=placeholder)
                 with gr.Row():
                     with gr.Column(scale=8):
                         textbox.render()