Refactor non-nullable entity properties to required

[bkoelman]

For example, change:

public string LastName { get; set; } = null!;

to:

public required string LastName { get; set; }

Should also update in README.md, documentation, etc.

[Jonesgodwin]

@bkoelman I'll do this in code and README.md But i don't know where should i update in the documentation.I don't know where is the documentation in the first place

[bkoelman]

Hi @Jonesgodwin, thanks for offering to help with this!

The documentation can be found in the /docs directory, in the form of markdown files and home/index.html. If you want, you can view the site locally by running build-dev.ps1.