Set correct PackageDescription

Author: eNeRGy164

src/libraries/System.Composition.AttributedModel/src/System.Composition.AttributedModel.csproj

@@ -5,17 +5,10 @@
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <UseCompilerGeneratedDocXmlFile>false</UseCompilerGeneratedDocXmlFile>
     <IsPackable>true</IsPackable>
-    <PackageDescription>Provides common attributes used by System.Composition types.
-
-Commonly Used Types:
-System.Composition.ExportAttribute
-System.Composition.ImportAttribute
-System.Composition.Convention.AttributedModelProvider</PackageDescription>
+    <PackageDescription>Provides the foundational attributes that allow you to declare parts for composition, such as imports, exports, and metadata with the Managed Extensibility Framework (MEF).</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>

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

@@ -8,7 +8,7 @@
     <NoWarn>$(NoWarn);NU5128</NoWarn>
     <!-- Reference dependencies to persiste them in the project's project.assets.json file which is used to calculate package dependencies. -->
     <NoTargetsDoNotReferenceOutputAssemblies>false</NoTargetsDoNotReferenceOutputAssemblies>
-    <PackageDescription>Provides the foundational attributes that allow you to declare parts for composition, such as imports, exports, and metadata with the Managed Extensibility Framework (MEF).</PackageDescription>
+    <PackageDescription>Provides a version of the Managed Extensibility Framework (MEF) that is lightweight and specifically optimized for high throughput scenarios, such as the web.</PackageDescription>
     <!-- TODO https://github.com/dotnet/runtime/issues/90400: Annotate for nullable reference types -->
     <Nullable>disable</Nullable>
     <NoWarn>$(NoWarn);nullable</NoWarn>