mention the domain sort option

Author: Fil

src/transforms/group.d.ts

@@ -127,7 +127,8 @@ export function groupZ<T>(outputs?: GroupOutputs, options?: T): Transformed<T>;
  *
  * The outputs may also include *filter* and *sort* options (with *reverse*) to
  * specify which groups are generated. Use filter: null to generate empty
- * groups, for example to impute sum=0 for a line chart.
+ * groups, for example to impute sum=0 for a line chart. The *sort* option can
+ * also target the domain of an associated scale such as *x*, *fx* or *fy*.
  *
  * See also **groupZ**, **groupY**, and **group** if you need to group by
  * series, *y*, or both *x* and *y*.
@@ -183,7 +184,8 @@ export function groupX<T>(outputs?: GroupOutputs, options?: T): Transformed<T>;
  *
  * The outputs may also include *filter* and *sort* options (with *reverse*) to
  * specify which groups are generated. Use filter: null to generate empty
- * groups, for example to impute sum=0 for a line chart.
+ * groups, for example to impute sum=0 for a line chart. The *sort* option can
+ * also target the domain of an associated scale such as *y*, *fx* or *fy*.
  *
  * See also **groupZ**, **groupX**, and **group** if you need to group by
  * series, *x*, or both *x* and *y*.