Update legal notes

Author: Feichtmeier

lib/constants.dart

@@ -42,3 +42,7 @@ const kHighlightColor = Colors.white;
 
 const kYaruTutorialMarkDown =
     'https://raw.githubusercontent.com/ubuntu-flutter-community/yaru_tutorial/master/README.md';
+
+const kLegalNote = 'Ubuntu is a registered trademark of Canonical Ltd';
+const kLegalLabel =
+    'Ubuntu Flutter Community is not officially endorsed by Canonical Ltd';

lib/legal_page.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 
+import 'constants.dart';
 import 'sub_page.dart';
 
 class LegalPage extends StatelessWidget {
@@ -12,8 +13,8 @@ class LegalPage extends StatelessWidget {
         child: Column(
           mainAxisSize: MainAxisSize.min,
           children: [
-            const Text('Ubuntu is a registered trademark of Canonical Ltd'),
-            const Text('Ubuntu Flutter Community is not Canonical Ltd'),
+            const Text(kLegalNote),
+            const Text(kLegalLabel),
           ]
               .map(
                 (e) => Padding(

lib/logo.dart

@@ -60,6 +60,7 @@ class _LogoState extends State<Logo> with SingleTickerProviderStateMixin {
             radius: widget.size / 10,
             child: Icon(
               YaruIcons.ubuntu_logo_simple,
+              color: Colors.white,
               size: (widget.size / 10) * 1.5,
             ),
           ),