Provide System.CodeDom package readme (#107372)

* Provide System.CodeDom package readme

* Add remark about Roslyn/.NET Compiler SDK

* Update src/libraries/System.CodeDom/src/PACKAGE.md

---------

Co-authored-by: Buyaa Namnan <buyankhishig.namnan@microsoft.com>

Author: eNeRGy164

src/libraries/System.CodeDom/src/PACKAGE.md

@@ -0,0 +1,127 @@
+## About
+
+<!-- A description of the package and where one can find more documentation -->
+
+Provides functionality for dynamically generating and compiling source code using the Code Document Object Model (CodeDOM).
+
+It allows developers to represent code in a language-agnostic format and then generate code in multiple languages, such as C# and VB.NET.
+The primary use cases include creating dynamic code generation tools, runtime code generation, and facilitating code analysis or transformation.
+
+For a new modern development consider using the [.NET Compiler Platform SDK](https://learn.microsoft.com/dotnet/csharp/roslyn-sdk/), in particular [Roslyn source generators](https://learn.microsoft.com/dotnet/csharp/roslyn-sdk/source-generators-overview#get-started-with-source-generators).
+
+## Key Features
+
+<!-- The key features of this package -->
+
+* Write code using a common object model that can be translated into multiple programming languages.
+* Generate and compile code at runtime based on the CodeDOM.
+
+## 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 -->
+
+Generating and compiling C# code:
+
+```csharp
+using System.CodeDom;
+using System.CodeDom.Compiler;
+using Microsoft.CSharp;
+
+// Create a new CodeCompileUnit to hold the code
+var compileUnit = new CodeCompileUnit();
+
+// Create a namespace
+var codeNamespace = new CodeNamespace("MyNamespace");
+compileUnit.Namespaces.Add(codeNamespace);
+
+// Create a class
+var classDeclaration = new CodeTypeDeclaration("MyClass")
+{
+    IsClass = true
+};
+codeNamespace.Types.Add(classDeclaration);
+
+// Add a simple method to the class
+var method = new CodeMemberMethod
+{
+    Name = "HelloWorld",
+    ReturnType = new CodeTypeReference(typeof(void)),
+};
+classDeclaration.Members.Add(method);
+
+var methodInvocation = new CodeMethodInvokeExpression(new CodeTypeReferenceExpression("Console"),
+                                                      "WriteLine",
+                                                      new CodePrimitiveExpression("Hello, World!"));
+method.Statements.Add(methodInvocation);
+
+// Generate C# code from the CodeDOM structure
+CodeDomProvider provider = new CSharpCodeProvider();
+
+using (var writer = new StringWriter())
+{
+    var codeGenereationOptions = new CodeGeneratorOptions()
+    {
+        BlankLinesBetweenMembers = false,
+        IndentString = "  ",
+    };
+
+    provider.GenerateCodeFromCompileUnit(compileUnit, writer, codeGenereationOptions);
+    Console.WriteLine(writer.GetStringBuilder().ToString());
+}
+```
+
+This example generates:
+
+```csharp
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace MyNamespace {
+
+  public class MyClass {
+    private void HelloWorld() {
+      Console.WriteLine("Hello, World!");
+    }
+  }
+}
+```
+
+## Main Types
+
+<!-- The main types provided in this library -->
+
+The main types provided by this library are:
+
+* `System.CodeDom.CodeObject`
+* `System.CodeDom.CodeCompileUnit`
+* `System.CodeDom.CodeNamespace`
+* `System.CodeDom.CodeTypeDeclaration`
+* `System.CodeDom.CodeMemberMethod`
+* `System.CodeDom.CodeTypeReference`
+* `System.CodeDom.CodeMethodInvokeExpression`
+* `System.CodeDom.CodeTypeReferenceExpression`
+* `System.CodeDom.CodePrimitiveExpression`
+* `System.CodeDom.Compiler.CodeDomProvider`
+* `System.CodeDom.Compiler.CodeGeneratorOptions`
+* `Microsoft.CSharp.CSharpCodeProvider`
+* `Microsoft.VisualBasic.VBCodeProvider`
+
+## Additional Documentation
+
+<!-- Links to further documentation. Remove conceptual documentation if not available for the library. -->
+
+* [API documentation](https://learn.microsoft.com/dotnet/api/system.codedom)
+* [Compile and generate dynamic source code](https://learn.microsoft.com/dotnet/framework/reflection-and-codedom/dynamic-source-code-generation-and-compilation)
+
+## Feedback & Contributing
+
+<!-- How to provide feedback on this package and contribute to it -->
+
+System.CodeDom 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.CodeDom/src/System.CodeDom.csproj

@@ -6,19 +6,11 @@
     <IsTrimmable>false</IsTrimmable>
     <UseCompilerGeneratedDocXmlFile>false</UseCompilerGeneratedDocXmlFile>
     <IsPackable>true</IsPackable>
-    <PackageDescription>Provides types that can be used to model the structure of a source code document and to output source code for that model in a supported language.
-
-Commonly Used Types:
-System.CodeDom.CodeObject
-System.CodeDom.Compiler.CodeDomProvider
-Microsoft.CSharp.CSharpCodeProvider
-Microsoft.VisualBasic.VBCodeProvider</PackageDescription>
+    <PackageDescription>Provides types that can be used to model the structure of a source code document and to output source code for that model in C# or Visual Basic.</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>
 
   <!-- DesignTimeBuild requires all the TargetFramework Derived Properties to not be present in the first property group. -->