add model training dataset details and usage notes

app.py

@@ -36,7 +36,8 @@ def translate(text: str, beam_size: int = 4) -> str:
 with gr.Blocks(title="Transformer From Scratch Translation Demo") as demo:
     gr.Markdown(
         "# Transformer From Scratch Translation Demo\n"
-        "Translate English to German using a custom Transformer model trained from scratch."
+        "Translate English to German using a custom Transformer model trained from scratch.\n\n"
+        "**Note:** This model was trained on the WMT14 English-German news dataset. It works best on formal, news-style sentences and may not perform well on everyday informal or conversational text."
     )
     with gr.Row(equal_height=True):
         with gr.Column():