fix(typings): Add "clear" as valid option for type

src/aurelia-binding.d.ts

@@ -184,7 +184,7 @@ export declare interface ICollectionObserverSplice<T = any, K = any> {
  value: T;

  /**
   * The type of change that has taken place. Valid options are "add", "delete", and "update".
   * The type of change that has taken place. Valid options are "add", "delete", "update", and  "clear".
   * 
   * *Note:* "update" is invalid for Set.
   *