docs(service-worker): update default value of SwRegistrationOptions#registrationStrategy (#37555)

The default value was changed from `registerWhenStable` to
`registerWhenStable:30000` in 29e8a64cf0,
but the decumentation was not updated to reflect that.

This commit updates the documentation to mention the correct default
value.

PR Close #37555

packages/service-worker/src/module.ts

@@ -70,7 +70,7 @@ export abstract class SwRegistrationOptions {
    *     The function will be used at runtime to obtain and subscribe to the `Observable` and the
    *     ServiceWorker will be registered as soon as the first value is emitted.
    *
-   * Default: 'registerWhenStable'
+   * Default: 'registerWhenStable:30000'
    */
   registrationStrategy?: string|(() => Observable<unknown>);
 }