docs: fix nix-darwin module configuration example

The example is missing a `;` which causes this error when you attempt
a `darwin-rebuild switch`.

```
       error: syntax error, unexpected '=', expecting ';'

       at /Users/968713/.nixpkgs/darwin-configuration.nix:17:30:

           16|   }
           17|   home-manager.users.eve = { pkgs, ... }: {
             |                              ^
           18|     home.packages = [
```

docs/manual/installation/nix-darwin.md

@@ -38,7 +38,7 @@ For example, a nix-darwin configuration may include the lines
 users.users.eve = {
   name = "eve";
   home = "/Users/eve";
-}
+};
 home-manager.users.eve = { pkgs, ... }: {
   home.packages = [ pkgs.atool pkgs.httpie ];
   programs.bash.enable = true;