Provide System.Composition.Convention package readme (dotnet#106782)

* Provide System.Composition.Convention package readme

* Improve after feedback

Author: eNeRGy164

src/libraries/System.Composition.Convention/src/PACKAGE.md

@@ -0,0 +1,97 @@
+## About
+
+<!-- A description of the package and where one can find more documentation -->
+
+`System.Composition.Convention` is part of the Managed Extensibility Framework (MEF) 2.0, a composition library for .NET that enables dependency injection through attributes or conventions.
+
+This package simplifies the process of applying consistent patterns for part exports, imports, and metadata by using convention-based configurations.
+It is useful for scenarios where you want to avoid repetitive attribute-based decoration and instead define conventions for registering types in your composition container.
+
+## Key Features
+
+<!-- The key features of this package -->
+
+* Configure exports, imports, and metadata for parts using conventions rather than attributes.
+* Allows defining conventions through a fluent API, making configuration more flexible and readable.
+
+## How to Use
+
+<!-- A compelling example on how to use this package with code, as well as any specific guidelines for when to use the package -->
+
+Configure parts for composition without using attributes.
+
+```csharp
+using System.Composition.Convention;
+using System.Composition.Hosting;
+
+var conventions = new ConventionBuilder();
+
+// Apply conventions: any class that implements ILogger will be exported as ILogger
+conventions
+    .ForTypesDerivedFrom<ILogger>()
+    .Export<ILogger>();
+
+var configuration = new ContainerConfiguration()
+    .WithPart<FileLogger>(conventions)
+    .WithPart<ConsoleLogger>(conventions);
+
+using CompositionHost container = configuration.CreateContainer();
+    
+var loggers = container.GetExports<ILogger>();
+
+foreach (var logger in loggers)
+{
+    logger.Log("Hello, World!");
+}
+// FileLogger: Hello, World!
+// ConsoleLogger: Hello, World!
+
+public interface ILogger
+{
+    void Log(string message);
+}
+
+public class FileLogger : ILogger
+{
+    public void Log(string message) => Console.WriteLine($"FileLogger: {message}");
+}
+
+public class ConsoleLogger : ILogger
+{
+    public void Log(string message) => Console.WriteLine($"ConsoleLogger: {message}");
+}
+```
+
+## Main Types
+
+<!-- The main types provided in this library -->
+
+The main types provided by this library are:
+
+* `System.Composition.Convention.ConventionBuilder`
+* `System.Composition.Convention.PartConventionBuilder`
+* `System.Composition.Convention.ParameterImportConventionBuilder`
+
+## Additional Documentation
+
+<!-- Links to further documentation. Remove conceptual documentation if not available for the library. -->
+
+* [API documentation](https://learn.microsoft.com/dotnet/api/system.composition.convention)
+* [Managed Extensibility Framework (MEF)](https://learn.microsoft.com/dotnet/framework/mef/)
+
+## Related Packages
+
+<!-- The related packages associated with this package -->
+
+* [System.Composition](https://www.nuget.org/packages/System.Composition)
+* [System.Composition.AttributedModel](https://www.nuget.org/packages/System.Composition.AttributedModel)
+* [System.Composition.Hosting](https://www.nuget.org/packages/System.Composition.Hosting)
+* [System.Composition.Runtime](https://www.nuget.org/packages/System.Composition.Runtime)
+* [System.Composition.TypedParts](https://www.nuget.org/packages/System.Composition.TypedParts)
+
+## Feedback & Contributing
+
+<!-- How to provide feedback on this package and contribute to it -->
+
+System.Composition.Convention is released as open source under the [MIT license](https://licenses.nuget.org/MIT).
+Bug reports and contributions are welcome at [the GitHub repository](https://github.com/dotnet/runtime).

src/libraries/System.Composition.Convention/src/System.Composition.Convention.csproj

@@ -6,19 +6,10 @@
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <UseCompilerGeneratedDocXmlFile>false</UseCompilerGeneratedDocXmlFile>
     <IsPackable>true</IsPackable>
-    <PackageDescription>Provides types that support using Managed Extensibility Framework with a convention-based configuration model.
-
-Commonly Used Types:
-System.Composition.Convention.ConventionBuilder
-System.Composition.Convention.ExportConventionBuilder
-System.Composition.Convention.ImportConventionBuilder
-System.Composition.Convention.PartConventionBuilder
-System.Composition.Convention.ParameterImportConventionBuilder</PackageDescription>
+    <PackageDescription>Provides types that support using Managed Extensibility Framework (MEF) with a convention-based configuration model.</PackageDescription>
     <!-- TODO https://github.com/dotnet/runtime/issues/90400: Annotate for nullable reference types -->
     <Nullable>disable</Nullable>
     <NoWarn>$(NoWarn);nullable</NoWarn>
-    <!-- TODO: Add package README file: https://github.com/dotnet/runtime/issues/99358 -->
-    <EnableDefaultPackageReadmeFile>false</EnableDefaultPackageReadmeFile>
   </PropertyGroup>
 
   <ItemGroup>