Add supported OS platform annotations

ElectronNET.API/Entities/OpenExternalOptions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.ComponentModel;
+using System.Runtime.Versioning;
 
 namespace ElectronNET.API.Entities
 {
@@ -12,11 +13,13 @@ namespace ElectronNET.API.Entities
         /// <see langword="true"/> to bring the opened application to the foreground. The default is <see langword="true"/>.
         /// </summary>
         [DefaultValue(true)]
+        [SupportedOSPlatform("macos")]
         public bool Activate { get; set; } = true;
 
         /// <summary>
         /// The working directory.
         /// </summary>
+        [SupportedOSPlatform("windows")]
         public string WorkingDirectory { get; set; }
     }
 }