Make Address value object truly immutable. Update implement-value-objects.md

[Alexbits]

It's better to remove private property setters to make Address value object truly immutable. Otherwise, it's possible to change the object by setting properties inside its methods for example.

protected override IEnumerable<object> GetAtomicValues()
    {
       Street = "Blah blah blah";
       City = "Blah blah blah";

        // Using a yield return statement to return each element one at a time
        yield return Street;
        yield return City;
        yield return State;
        yield return Country;
        yield return ZipCode;
    }

Summary

Remove private property setters. Make public properties readonly.

Fixes #Issue_Number (if available)

[jzeferino]

LGTM.

[BillWagner]

Thanks for updating this @Alexbits We appreciate it.

I've reviewed the changes, and I'm going to now.

Pinging @CESARDELATORRE as these changes should make it to the reference application as well.