Provide System.ServiceModel.Syndication package readme

src/libraries/System.ServiceModel.Syndication/src/PACKAGE.md

@@ -2,43 +2,124 @@
 
 <!-- A description of the package and where one can find more documentation -->
 
-
+Provides types for generating and consuming RSS and Atom feeds.
+It is used for creating and parsing syndication feeds, making it easier to build and integrate web content syndication.
 
 ## Key Features
 
 <!-- The key features of this package -->
 
-*
-*
-*
+* Easy generation and parsing of RSS and Atom feeds.
+* Customizable for different syndication needs.
+* Support for both feed reading and writing.
 
 ## 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 -->
 
+### Creating a Feed
+
+```csharp
+using System.ServiceModel.Syndication;
+using System.Xml;
+
+// Create a new syndication feed
+SyndicationFeed feed = new SyndicationFeed(
+    "Feed Title",
+    "Feed Description",
+    new Uri("http://example.com"),
+    "FeedID",
+    DateTime.Now);
+
+// Add items to the feed
+SyndicationItem item1 = new SyndicationItem(
+    "Title1",
+    "Content1",
+    new Uri("http://example.com/item1"));
+feed.Items = new List<SyndicationItem> { item1 };
+
+// Serialize the feed to RSS format
+using (XmlWriter writer = XmlWriter.Create("rss.xml"))
+{
+    Rss20FeedFormatter rssFormatter = new Rss20FeedFormatter(feed);
+    rssFormatter.WriteTo(writer);
+}
+```
+
+Resulting RSS feed:
+
+```xml
+<?xml version="1.0" encoding="utf-8"?>
+<rss xmlns:a10="http://www.w3.org/2005/Atom" version="2.0">
+    <channel>
+        <title>Feed Title</title>
+        <link>http://example.com/</link>
+        <description>Feed Description</description>
+        <lastBuildDate>Sat, 11 Nov 2023 18:05:21 +0100</lastBuildDate>
+        <a10:id>FeedID</a10:id>
+        <item>
+            <link>http://example.com/item1</link>
+            <title>Title1</title>
+            <description>Content1</description>
+        </item>
+    </channel>
+</rss>
+```
+
+### Consuming a Feed
+
+```csharp
+using System.ServiceModel.Syndication;
+using System.Xml;
+
+string feedUrl = "https://devblogs.microsoft.com/dotnet/feed/";
+using XmlReader reader = XmlReader.Create(feedUrl);
+
+// Read the feed using Atom10FeedFormatter.
+SyndicationFeed feed = SyndicationFeed.Load(reader);
+
+Console.WriteLine($"Feed Title: {feed.Title.Text}");
+Console.WriteLine("Feed Items:");
+
+// Iterate through the feed items and display the title and a brief summary of each.
+foreach (SyndicationItem item in feed.Items)
+{
+    Console.WriteLine($"Title: {item.Title.Text}");
+    Console.WriteLine($"Published Date: {item.PublishDate.DateTime}");
+}
+
+/*
+ * This code produces the following output:
+ *
+ * Feed Title: .NET Blog
+ * Feed Items:
+ * - Title: Join us for the Great .NET 8 Hack
+ *   Published Date: 07/11/2023 18:05:00
+ * - Title: The convenience of System.IO
+ *   Published Date: 06/11/2023 18:05:00
+ */
+```
+
 ## Main Types
 
 <!-- The main types provided in this library -->
 
 The main types provided by this library are:
 
-* ``
-* ``
-* ``
+* `System.ServiceModel.Syndication.SyndicationFeed`
+* `System.ServiceModel.Syndication.SyndicationItem`
+* `System.ServiceModel.Syndication.Rss20FeedFormatter`
+* `System.ServiceModel.Syndication.Atom10FeedFormatter`
 
 ## Additional Documentation
 
 <!-- Links to further documentation. Remove conceptual documentation if not available for the library. -->
 
-* [Conceptual documentation](https://learn.microsoft.com/dotnet/standard/serialization/**LIBRARYNAME**/overview)
-* [API documentation](https://learn.microsoft.com/dotnet/api/**LIBRARYNAME**)
-
-## Related Packages
-
-<!-- The related packages associated with this package -->
+* [Conceptual documentation](https://learn.microsoft.com/dotnet/framework/wcf/feature-details/how-to-create-a-basic-rss-feed)
+* [API documentation](https://learn.microsoft.com/dotnet/api/system.servicemodel.syndication)
 
 ## Feedback & Contributing
 
 <!-- How to provide feedback on this package and contribute to it -->
 
-System.ServiceModel.Syndication 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).
+System.ServiceModel.Syndication 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).