Update outdated Angular tutorial document.

[maliming]

https://abp.io/docs/latest/tutorials/book-store/part-02?UI=NG&DB=EF

The BookStore tutorial for Angular seems to be outdated

as it still refers to using modules even though the Angular template does not do that anymore as recommended by the Angular team

yarn ng generate module book --module app --routing --route books
etc.

the angular app generated by latest ABP Studio does not use NgModule.