add usage instructions

app.py

@@ -4,11 +4,21 @@ from sqlalchemy import text
 from smolagents import tool, CodeAgent, HfApiModel
 import spaces
 import pandas as pd
-
 from database import engine, receipts
-
 import pandas as pd
 
+gr.Markdown("""
+## Plain Text Query Interface
+
+This tool allows you to query a receipts database using natural language. Simply type your question into the input box, and the tool will generate and execute an SQL query to retrieve relevant data. The results will be displayed in the output box.
+
+### How to Use:
+1. Enter a question related to the receipts data in the text box.
+2. The tool will convert your question into an SQL query and execute it.
+3. The result will be displayed in the output box.
+4. The current receipts table is also displayed for reference.
+""")
+
 def get_receipts_table():
     """
     Fetches all data from the 'receipts' table and returns it as a Pandas DataFrame.