Add instructions for advanced use

app.py

@@ -101,6 +101,12 @@ description = """
 *Inspired by [Unsplash Image Search](https://github.com/haltakov/natural-language-image-search) from Vladimir Haltakov and [Alph, The Sacred River](https://github.com/thoppe/alph-the-sacred-river) from Travis Hoppe*
 """
 
+howto = """
+- Click on an image to use it as a query and find similar images
+- Several queries, including one based on an image, can be combined (use "**;**" as a separator)
+- If the input includes "**/**", the part right of "**/**" will be used as a negative query
+"""
+
 
 def main():
     st.markdown(
@@ -137,6 +143,9 @@ def main():
         unsafe_allow_html=True,
     )
     st.sidebar.markdown(description)
+    with st.sidebar.expander("Advanced use"):
+        st.markdown(howto)
+
     _, c, _ = st.columns((1, 3, 1))
     if "query" in st.session_state:
         query = c.text_input("", value=st.session_state["query"])