Small fixes

Author: Panda-Sharp

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/SystemInformation/SystemInformationCode.bind

@@ -38,7 +38,7 @@
         public PackageVersion FirstVersionInstalled => SystemInformation.Instance.FirstVersionInstalled;
 
         // To get the previous version installed
-        public string PreviousVersionInstalled => SystemInformation.Instance.PreviousVersionInstalled.ToFormattedString();
+        public PackageVersion PreviousVersionInstalled => SystemInformation.Instance.PreviousVersionInstalled;
 
         // To get the first time the app was launched
         public DateTime FirstUseTime => SystemInformation.Instance.FirstUseTime;

Microsoft.Toolkit.Uwp/Helpers/SystemInformation.cs

@@ -124,7 +124,7 @@ public static async Task LaunchStoreForReviewAsync()
         /// <summary>
         /// Gets the previous version of the app that was installed.
         /// This will be the current version if a previous version of the app was installed
-        /// before using SystemInformation or if the app is not updated.
+        /// before using <see cref="SystemInformation"/>  or if the app is not updated.
         /// </summary>
         public PackageVersion PreviousVersionInstalled { get; }