Added some XML docs.

src/Avalonia.Diagnostics/DevToolsExtensions.cs

@@ -4,13 +4,25 @@ using Avalonia.Input;
 
 namespace Avalonia
 {
+    /// <summary>
+    /// Extension methods for attaching DevTools..
+    /// </summary>
     public static class DevToolsExtensions
     {
+        /// <summary>
+        /// Attaches DevTools to a window, to be opened with the F12 key.
+        /// </summary>
+        /// <param name="root">The window to attach DevTools to.</param>
         public static void AttachDevTools(this TopLevel root)
         {
             DevTools.Attach(root, new KeyGesture(Key.F12));
         }
 
+        /// <summary>
+        /// Attaches DevTools to a window, to be opened with the specified key gesture.
+        /// </summary>
+        /// <param name="root">The window to attach DevTools to.</param>
+        /// <param name="gesture">The key gesture to open DevTools.</param>
         public static void AttachDevTools(this TopLevel root, KeyGesture gesture)
         {
             DevTools.Attach(root, gesture);