Custom Scaffolding Templates

We should add a walkthrough showing how to obtain and tweak the default scaffolding templates.

```
dotnet new install Microsoft.EntityFrameworkCore.Templates
dotnet new ef-templates
```

A brief overview of T4 and a link to [those docs](https://docs.microsoft.com/en-us/visualstudio/modeling/code-generation-and-t4-text-templates?view=vs-2022) might also be useful.