Resolve "Allow additional content to ScreenAbout"

Closes #29 (closed)

lib/nav/ui/screens/about.dart

@@ -2,7 +2,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter_custom_toolbox/flutter_toolbox.dart';
 
 class ScreenAbout extends StatelessWidget {
-  const ScreenAbout({super.key});
+  const ScreenAbout({
+    super.key,
+    this.additionalContent,
+  });
+
+  final Widget? additionalContent;
 
   @override
   Widget build(BuildContext context) {
@@ -31,6 +36,7 @@ class ScreenAbout extends StatelessWidget {
               }
             },
           ),
+          additionalContent ?? SizedBox.shrink(),
         ],
       ),
     );