Add short code to show how to add the module

[HarelM]

Most libraries have a short section to show how to add the relevant module to angular application module.
I think it would be beneficial to new developers that would like to use this library like me.
For example, see the setup section here:
https://github.com/nicky-lenaers/ngx-scroll-to

[HarelM]

Probably css file instructions are needed too...

[aymeric-duchein]

Hi! To use this library, simply add AngularOpenLayersModule to your module

@NgModule({
  ...
  imports: [
    ...
    AngularOpenlayersModule,
    ...
  ],
  ...
})
export class AppModule { }

If you think something is missing, a PR to improve the documentation is always welcome!

[HarelM]

Feel free to accept it :-)