fix typo preamble

Author: yibeichan

reproschema/redcap2reproschema.py

@@ -506,7 +506,7 @@ def process_row(
             if parsed_value:
                 rowData[schema_key] = parsed_value
 
-        elif schema_key == "preamble" and add_preable:
+        elif schema_key == "preamble" and add_preamble:
             parsed_value = parse_html(value)
             if parsed_value:
                 rowData[schema_key] = parsed_value