chore(core): fix typo in assets.ts (#25548)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/aws-cdk-lib/core/lib/assets.ts

@@ -112,7 +112,7 @@ export interface FileAssetSource {
    *
    * The command should produce the location of a ZIP file on `stdout`.
    *
-   * @default - Exactly one of `directory` and `executable` is required
+   * @default - Exactly one of `fileName` and `executable` is required
    */
   readonly executable?: string[];
 
@@ -121,7 +121,7 @@ export interface FileAssetSource {
    * source resides. This can be a path to a file or a directory, depending on the
    * packaging type.
    *
-   * @default - Exactly one of `directory` and `executable` is required
+   * @default - Exactly one of `fileName` and `executable` is required
    */
   readonly fileName?: string;
 
@@ -386,4 +386,4 @@ export interface DockerCacheOption {
    * };
    */
   readonly params?: { [key: string]: string };
-}
+}