Document System.IO.EnumerationOptions (#3527)

Author: carlossanlop

xml/System.IO/EnumerationOptions.xml

@@ -18,7 +18,7 @@
   </Base>
   <Interfaces />
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Provides file and directory enumeration options.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>