Snippet2 missing method, generateXMLString (dotnet#8118)

//<Snippet2> is referenced by a documentation page for XmlDocument (see below for URLs). When the code copied from the documentation is pasted into a Windows Forms app and the namespaces added, the code does not compile. The compilation error is caused because one method is missing, generateXMLString. There is a copy button on documentation page which copies <Snippet2>. I moved generateXMLString from the top of xmlhelpermethods.cs where it is not used into //<Snippet2> so it will be included in the example code for the XmlDocument class.

//<Snippet2> is referenced by

https://docs.microsoft.com/en-us/dotnet/api/system.xml.xmldocument?view=net-6.0
https://github.com/dotnet/dotnet-api-docs/blob/main/xml/System.Xml/XmlDocument.xml

Here is where snippet 2 is referenced
 [!code-csharp[XMLProcessingApp#2](~/snippets/csharp/System.Xml/XmlDocument/Overview/xmlhelpermethods.cs#2)]

Author: softwarepronto

snippets/csharp/System.Xml/XmlDocument/Overview/xmlhelpermethods.cs

@@ -45,10 +45,24 @@ public XmlDocument LoadDocument(bool generateXML)
 
         //************************************************************************************
         //
-        //  Helper method that generates an XML string.
+        //  Loads XML from a file. If the file is not found, load XML from a string.
         //
         //************************************************************************************
+        public void SaveXML(XmlDocument doc)
+        {
+            doc.Save(Constants.booksFileName);
+        }
+        #endregion
+
+        #region Validate XML against a Schema
+
+        //<Snippet2>
 
+        //************************************************************************************
+        //
+        //  Helper method that generates an XML string.
+        //
+        //************************************************************************************
         private string generateXMLString()
         {
             string xml = "<?xml version=\"1.0\"?> \n" +
@@ -68,22 +82,7 @@ private string generateXMLString()
                 "</books>";
             return xml;
         }
-
-        //************************************************************************************
-        //
-        //  Loads XML from a file. If the file is not found, load XML from a string.
-        //
-        //************************************************************************************
-        public void SaveXML(XmlDocument doc)
-        {
-            doc.Save(Constants.booksFileName);
-        }
-        #endregion
-
-        #region Validate XML against a Schema
-
-        //<Snippet2>
-
+            
         //************************************************************************************
         //
         //  Associate the schema with XML. Then, load the XML and validate it against