Fix typos in promotion banner

Author: NotYoojun

source/iNKORE.UI.WPF.Modern.Gallery/Controls/UserControls/DocumentationPromotion.xaml

@@ -44,7 +44,7 @@
 
                     <TextBlock>
                                         <Run>It's very easy to join us! You can create a PR in our</Run>
-                                        <Hyperlink x:Name="Hyperlink_DoucmentationRepo" Click="Hyperlink_DoucmentationRepo_Click">Doucmentation repository</Hyperlink>
+                                        <Hyperlink x:Name="Hyperlink_DocumentationRepo" Click="Hyperlink_DocumentationRepo_Click">Documentation repository</Hyperlink>
                                         <Run>when you're free. You can also join our</Run>
                                         <Hyperlink x:Name="Hyperlink_Discord" Click="Hyperlink_Discord_Click">Discord server</Hyperlink>
                                         <Run>and</Run>
@@ -59,7 +59,7 @@
                     <ui:HyperlinkButton x:Name="HyperlinkButton_Repository" Content="Repository" Click="HyperlinkButton_Repository_Click"/>
                     <ui:HyperlinkButton x:Name="HyperlinkButton_Package" Content="Package" Click="HyperlinkButton_Package_Click"/>
 
-                    <ui:HyperlinkButton x:Name="HyperlinkButton_DocRepository" Content="Docs Repository" Click="Hyperlink_DoucmentationRepo_Click"/>
+                    <ui:HyperlinkButton x:Name="HyperlinkButton_DocRepository" Content="Docs Repository" Click="Hyperlink_DocumentationRepo_Click"/>
                     <ui:HyperlinkButton x:Name="HyperlinkButton_Facebook" Content="Follow us on Facebook!" Click="HyperlinkButton_Facebook_Click"/>
 
                 </ikw:SimpleStackPanel>

source/iNKORE.UI.WPF.Modern.Gallery/Controls/UserControls/DocumentationPromotion.xaml.cs

@@ -35,7 +35,7 @@ private void HyperlinkButton_Package_Click(object sender, RoutedEventArgs e)
             App.BrowseWeb(ThemeManager.Link_NugetPackage);
         }
 
-        private void Hyperlink_DoucmentationRepo_Click(object sender, RoutedEventArgs e)
+        private void Hyperlink_DocumentationRepo_Click(object sender, RoutedEventArgs e)
         {
             App.BrowseWeb("https://github.com/iNKORE-NET/Documentation/tree/main/data/docs/ui.wpf.modern");
         }