Earlier quoted context omitted.
A good example of what exactly? Because regarding (a), this is just a quick reference for options. Nothing more, nothing less. As for (b), you're literally looking at detailed documentation. It's almost as if you made up your mind before opening the link.
If nix/home-manager documentation wasnt awful this site wouldn't be needed. And the level of detail should be way better than a one line sentence with no examples.
https://nix-community.github.io/home-manager/options.xhtml
Or alternatively:
man home-configuration.nix
The official documentation does have examples.