docs(forms): clarify disabled FormArray value behavior

Document that FormArray.value includes only enabled child controls when the array is enabled, but includes all child values when the FormArray itself is disabled.

Fixes angular#67759

Author: angular-bootstrap

packages/forms/src/model/abstract_model.ts

@@ -554,7 +554,8 @@ export abstract class AbstractControl<
    * with a key-value pair for each member of the group.
    * * For a disabled `FormGroup`, the values of all controls as an object
    * with a key-value pair for each member of the group.
-   * * For a `FormArray`, the values of enabled controls as an array.
+   * * For an enabled `FormArray`, the values of enabled controls as an array.
+   * * For a disabled `FormArray`, the values of all controls as an array.
    *
    */
   public readonly value!: TValue;

packages/forms/src/model/form_array.ts

@@ -54,7 +54,8 @@ export type ɵFormArrayRawValue<T extends AbstractControl<any>> = ɵTypedOrUntyp
  *
  * A `FormArray` aggregates the values of each child `FormControl` into an array.
  * It calculates its status by reducing the status values of its children. For example, if one of
- * the controls in a `FormArray` is invalid, the entire array becomes invalid.
+ * the controls in a `FormArray` is invalid, the entire array becomes invalid. Similarly, if all
+ * controls in a `FormArray` are disabled, the entire array becomes disabled.
  *
  * `FormArray` accepts one generic argument, which is the type of the controls inside.
  * If you need a heterogenous array, use {@link UntypedFormArray}.