Clarify error message about schema

app.py

@@ -33,7 +33,7 @@ st.text(
     "Upload an Excel table and perform zero-shot classification on a set of custom labels"
 )
 
-data = st.file_uploader("Upload Excel file (it should contain a `text` column):")
+data = st.file_uploader("Upload Excel file (it should contain a column named `text` in its header):")
 labels = st.text_input("Enter comma-separated labels:")
 
 # classify first N snippets only for faster inference
@@ -59,5 +59,5 @@ if st.button("Calculate labels"):
 
     except:
         st.error(
-            "Something went wrong. Make sure you upload an Excel file containing a `text` column and a set of comma-separated labels is provided"
+            "Something went wrong. Make sure you upload an Excel file containing a column named `text` and a set of comma-separated labels is provided"
         )