Add docs for renaming tables/columns

I'd like to rename a table in Entity Framework Core, code first. I do not want to drop and create the table, as this would lose all my data. As I search for information on this, I see that the vast majority of it is outdated.

This best source I found is by [Mitchel Sellers](https://www.mitchelsellers.com/blog/article/renaming-tables-safely-in-entity-framework-core). But this also seems outdated. I'm not sure how much difference it makes but he declares his table as:

public DbSet Widgets { get; set; }

When the modern construct seems to use generics:

public DbSet Widgets { get; set; }

I also found several articles that recommend entering the migration code manually. But I don't think this is ideal. I know if it's done correctly, all the associated constraint names are renamed as well. I would prefer not to enter the migration manually.

Why doesn't Microsoft publish the current and correct steps to do this?