Update DestinationAlreadyExists warning

Change to "A file exists at the destination path."

Author: jcansdale

src/GitHub.App/ViewModels/Dialog/Clone/RepositoryCloneViewModel.cs

@@ -239,7 +239,6 @@ string ValidatePath(IRepositoryModel repository, string path)
         {
             if (repository != null)
             {
-                // TODO: Update wording for DestinationAlreadyExists
                 return service.DestinationFileExists(path) ?
                     Resources.DestinationAlreadyExists :
                     null;

src/GitHub.Resources/Resources.Designer.cs

@@ -331,7 +331,7 @@ https://git-scm.com/download/win</value>
     <value>Cancel Review</value>
   </data>
   <data name="DestinationAlreadyExists" xml:space="preserve">
-    <value>The destination already exists.</value>
+    <value>A file exists at the destination path.</value>
   </data>
   <data name="LogoutRequired" xml:space="preserve">
     <value>Logout Required</value>