fix: correct typo

Author: gururaj1512

lib/node_modules/@stdlib/plot/vega/transform/aggregate-facet/lib/main.js

@@ -204,7 +204,7 @@ setReadWriteAccessor( AggregateFacetTransform.prototype, 'cross', getCross, setC
 * var v = transform.fields;
 * // returns [ <Field>, <Field> ]
 */
-setReadWriteAccessor( AggregateFacetTransform.prototype, 'fields', getFields, sertFields );
+setReadWriteAccessor( AggregateFacetTransform.prototype, 'fields', getFields, setFields );
 
 /**
 * Aggregation operations to apply to the fields.