[Feature] optimise doc

[rbalet]

Is your feature request related to a problem? Please describe

If you initialise the NgcCookieConsentService in the AppComponent, then you subscribe to it there, you will never get a ngOnDestroy() therefore, it will kind of create this memory leak that the doc talk about

Describe the idea you'd like

As the cookie banner could be answered only once, we could user pipe(take(1)) instead.

Describe alternatives you've considered

No response

Additional context

No response