adding sample file to fn4b parser

apps/fnb_parser.py

@@ -252,6 +252,16 @@ def main() -> None:
         "Convert F4NB Word documents into a tidy Excel / DataFrame containing site & sector information.\n"
         "Upload one or many F4NB `.docx` files and hit **Process**."
     )
+    # Download Sample file
+    fnb_sample_file_path = "samples/FN4B.docx"
+
+    # Create a download button
+    st.download_button(
+        label="Download FNB Sample File",
+        data=open(fnb_sample_file_path, "rb").read(),
+        file_name="fnb.docx",
+        mime="application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+    )
 
     st.subheader("Upload Files")
     uploaded_files = st.file_uploader(