Document System.IO.Enumeration namespace (#3535)

* Document System.IO.Enumeration namespace

* Update xml/ns-System.IO.Enumeration.xml

Co-Authored-By: Genevieve Warren <[email protected]>

Author: 2 people

xml/ns-System.IO.Enumeration.xml

@@ -1,6 +1,6 @@
 <Namespace Name="System.IO.Enumeration">
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Provides classes, structs, and delegates to search and enumerate file system elements.</summary>
     <remarks>To be added.</remarks>
   </Docs>
 </Namespace>