Improve documentation and code of example

Signed-off-by: spnda <43609023+spnda@users.noreply.github.com>

example/example.dart

@@ -3,28 +3,28 @@ import 'dart:io';
 import 'package:dart_minecraft/dart_minecraft.dart';
 
 Future<int> main() async {
-  /// In this example we'll read content from a NBT File,
-  /// which in its root compound has a single NBT_String that
-  /// contains a UUID of a player, we'll get the skin texture from.
+  /// In this example we'll read content from a NBT File
+  /// which in its root compound has a single NbtString that
+  /// contains a UUID of a player we'll try and get the skin texture from.
   final nbtFile = NbtFile.fromPath('./example/data.nbt');
   try {
     await nbtFile.readFile();
   } on FileSystemException catch (e) {
     print(e);
     return -1;
   } on NbtFileReadException {
-    print('Cannot read data.nbt');
+    print('Failed to read data.nbt');
   }
 
-  /// If the file doesn't exist we'll replace the file with some example
-  /// data. This is how one would create nbt data using this package.
+  /// If the file doesn't exist we'll instead use some example data.
+  /// This shows how one would create nbt data using this package.
   nbtFile.root ??= NbtCompound(
     name: '',
     children: [
       NbtString(
-          name: 'uuid',
-          value: '069a79f444e94726a5befca90e38aaf5' // This is Notch's UUID.
-          )
+        name: 'uuid',
+        value: '069a79f444e94726a5befca90e38aaf5', // This is Notch's UUID.
+      ),
     ],
   );
 
@@ -36,10 +36,11 @@ Future<int> main() async {
   if (nbtString == null) return -1;
   final profile = await Mojang.getProfile(nbtString.value);
   final skinUrl = profile.textures.getSkinUrl();
-  print(skinUrl); // URL to Notch's skin texture.
+  print("Notch's Skin URL: $skinUrl"); // URL to Notch's skin texture.
 
   /// As we've now got the URL for the texture, we'll write the link to
   /// it to our previously read nbt file and re-write it to the file.
+  nbtFile.root!.removeWhere((tag) => tag.name == 'skinUrl');
   nbtFile.root!.add(NbtString(name: 'skinUrl', value: skinUrl));
   await nbtFile.writeFile();
   return 0;