Updated Microsoft.AspNetCore.Identity.UserOptions.RequireUniqueEmail flag XML docs description (#46552)

Author: KamilRaszkiewicz

src/Identity/Extensions.Core/src/UserOptions.cs

@@ -20,7 +20,7 @@ public class UserOptions
     /// Gets or sets a flag indicating whether the application requires unique emails for its users. Defaults to false.
     /// </summary>
     /// <value>
-    /// True if the application requires each user to have their own, unique email, otherwise false.
+    /// True if the application requires each user to have their own, unique, not null, not blank email, otherwise false.
     /// </value>
     public bool RequireUniqueEmail { get; set; }
 }