Provide xsd tool example with /classes option (dotnet#42685)

Author: BartoszKlonowski

docs/standard/serialization/xml-schema-def-tool-gen.md

@@ -23,10 +23,11 @@ _C:\\Program Files (x86)\\Microsoft SDKs\\Windows\\{version}\\bin\\NETFX {versio
 2. Pass the XML Schema as an argument to the XML Schema Definition tool, which creates a set of classes that are precisely matched to the XML Schema, for example:  
 
     ```console  
-    xsd mySchema.xsd  
+    xsd mySchema.xsd /classes
     ```  
-  
-     The tool can only process schemas that reference the World Wide Web Consortium XML specification of March 16, 2001. In other words, the XML Schema namespace must be `"http://www.w3.org/2001/XMLSchema"`, as shown in the following example.  
+
+    (The `/classes` option in this command is used to generate classes for the `mySchema` schema.)
+    The tool can only process schemas that reference the World Wide Web Consortium XML specification of March 16, 2001. In other words, the XML Schema namespace must be `"http://www.w3.org/2001/XMLSchema"`, as shown in the following example.  
   
     ```xml  
     <?xml version="1.0" encoding="utf-8"?>