docs: add TSDoc for cancelable promise list methods (#988)

Author: sarahdayan

packages/autocomplete-core/src/utils/createCancelablePromiseList.ts

@@ -1,8 +1,22 @@
 import { CancelablePromise } from '.';
 
 export type CancelablePromiseList<TValue> = {
+  /**
+   * Add a cancelable promise to the list.
+   *
+   * @param cancelablePromise The cancelable promise to add.
+   */
   add(cancelablePromise: CancelablePromise<TValue>): CancelablePromise<TValue>;
+  /**
+   * Cancel all pending promises.
+   *
+   * Requests aren't actually stopped. All pending promises will settle, but
+   * attached handlers won't run.
+   */
   cancelAll(): void;
+  /**
+   * Whether there are pending promises in the list.
+   */
   isEmpty(): boolean;
 };