The new `storage.create()` method has ambiguous behavior / documentation

In the new `@ionic/storage` API, particularly when using the `storage-angular` module, the behavior of the `storage.create()` method is unclear.

It appears in some parts of the documentation that this method could/should be used to create a new instance of `Storage` that is held and maintained by a central Angular service. Yet in other parts of the documentation, it appears it is enough just to inject the Provider `Storage` into components & services.

The `create()` method needs to be called at least once even is using the direct injection approach, and it's not clear what happens if `create()` is called multiple times. Particularly if the service is injected vs. not injected, etc.

It would be great if the docs could be clarified so that we know when to call `create()` or not. Does it only need to be called once per application, or once every place `Storage` is injected? And what are the consequences of calling it multiple times, even if the return value is ignored?

Thanks!

Esamina la documentazione di @ionic/storage e storage-angular insieme all’utilizzo di create() descritto nell’issue. Chiarisci quando create() è necessario, se è applicabile a tutta l’applicazione o è specifico dell’iniezione e cosa fanno le chiamate ripetute; la documentazione è completa quando questi casi e le loro conseguenze sono indicati in modo coerente.

Scritto dal modello di indicizzazione a partire dal testo della issue.