Fix typo

src/Avalonia.Base/Rect.cs

@@ -243,7 +243,7 @@ namespace Avalonia
         }
 
         /// <summary>
-        /// Determines whether a point in in the bounds of the rectangle.
+        /// Determines whether a point is in the bounds of the rectangle.
         /// </summary>
         /// <param name="p">The point.</param>
         /// <returns>true if the point is in the bounds of the rectangle; otherwise false.</returns>