Add docs for ThemeSelectorResult (OrchardCMS#11147)

Co-authored-by: Dean Marcussen <dean.marcussen@gmail.com>

src/OrchardCore/OrchardCore.DisplayManagement/Theming/ThemeSelectorResult.cs

@@ -1,8 +1,19 @@
 namespace OrchardCore.DisplayManagement.Theming
 {
+    /// <summary>
+    /// Represents a result for a selected theme.
+    /// </summary>
     public class ThemeSelectorResult
     {
+        /// <summary>
+        /// Gets or sets the priority for the selected theme.
+        /// </summary>
         public int Priority { get; set; }
+
+        /// <summary>
+        /// Gets or sets the theme name.
+        /// </summary>
+        /// <remarks>This is the theme identifier. By default this is also the theme name, but if a custom identifier has been specified, please use the identifier.</remarks>
         public string ThemeName { get; set; }
     }
 }