add ConfigurationIgnoreAttribute to docs

docs/core/extensions/configuration.md

@@ -1,7 +1,7 @@
 ---
 title: Configuration
 description: Learn how to use the Configuration API to configure .NET applications. Explore various inbuilt configuration providers.
-ms.date: 10/09/2024
+ms.date: 08/27/2026
 ms.topic: overview
 ai-usage: ai-assisted
 ---
@@ -118,6 +118,7 @@ The configuration binder has specific behaviors and limitations when working wit
 - [Bind to dictionaries](#bind-to-dictionaries)
 - [Dictionary keys with colons](#dictionary-keys-with-colons)
 - [Bind to IReadOnly* types](#bind-to-ireadonly-types)
+- [Exclude properties from binding](#exclude-properties-from-binding)
 - [Bind with parameterized constructors](#bind-with-parameterized-constructors)
 
 #### Bind to dictionaries
@@ -152,6 +153,14 @@ The configuration class implementation:
 
 This approach allows the binder to populate the mutable `List<string>` while presenting an immutable interface to consumers through `IReadOnlyList<string>`.
 
+#### Exclude properties from binding
+
+If you don't want the configuration binder to populate a property, apply <xref:Microsoft.Extensions.Configuration.ConfigurationIgnoreAttribute> to it (available starting in .NET 11).
+
+:::code language="csharp" source="snippets/configuration/binding-scenarios/ConfigurationIgnore/Program.cs" id="AppOptions":::
+
+If configuration contains values for both `Endpoint` and `RuntimeValue`, the binder updates `Endpoint` and leaves `RuntimeValue` at its existing value.
+
 #### Bind with parameterized constructors
 
 Starting with .NET 7, the configuration binder supports binding to types with a single public parameterized constructor. This enables immutable types and records to be populated directly from configuration:

docs/core/extensions/snippets/configuration/binding-scenarios/ConfigurationIgnore/ConfigurationIgnore.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net11.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
+  </ItemGroup>
+
+</Project>

docs/core/extensions/snippets/configuration/binding-scenarios/ConfigurationIgnore/Program.cs

@@ -0,0 +1,29 @@
+// <AppOptions>
+using Microsoft.Extensions.Configuration;
+
+public sealed class AppOptions
+{
+    public string Endpoint { get; set; } = "";
+
+    [ConfigurationIgnore]
+    public string RuntimeValue { get; set; } = "calculated";
+}
+// </AppOptions>
+
+public static class Program
+{
+    public static void Main()
+    {
+        var configuration = new ConfigurationManager
+        {
+            [nameof(AppOptions.Endpoint)] = "https://localhost",
+            [nameof(AppOptions.RuntimeValue)] = "configured",
+        };
+
+        var options = new AppOptions();
+        configuration.Bind(options);
+
+        Console.WriteLine($"Endpoint: {options.Endpoint}");
+        Console.WriteLine($"RuntimeValue: {options.RuntimeValue}");
+    }
+}