Add more examples of how to use the configuration options

[BBlackwo]

As mentioned by @bdspen in https://github.com/btroncone/ngrx-store-localstorage/issues/144#issuecomment-611558226. Opening a new issue specifically for the lack of config option examples.

If I might add, as a new user of the library I think it would be really nice to have more code examples of common configurations and usages of the library.

Something using mergeReducer, storage, and some of the other configurations like serialize and others in that list would be good too.

I did some experimenting with these properties to see what the library is capable of, but it would have been easier to look at some real world code samples.

Maybe there could be an examples folder with sample files?

I think a lot more info could be added to the README with some more examples, and if that's not enough potentially an examples folder too.

[BBlackwo]

Here's a good example of how to use the mergeReducer function if you don't want the state cloned. https://github.com/btroncone/ngrx-store-localstorage/issues/128#issuecomment-613975060