Fix docs for generic custom json converter (#1909)

The previous text was for the non generic custom json converter sample (probably copy/paste error).

Doc/Samples/Serializer/CustomJsonConverterGeneric.aml

@@ -3,7 +3,7 @@
   <developerConceptualDocument xmlns="http://ddue.schemas.microsoft.com/authoring/2003/5" xmlns:xlink="http://www.w3.org/1999/xlink">
     <introduction>
       <para>This sample creates a custom <codeEntityReference>T:Newtonsoft.Json.JsonConverter{T}</codeEntityReference>
-      that overrides serialization to add a keys property.</para>
+      that overrides serialization for the Version property with a custom display string.</para>
     </introduction>
     <section>
       <title>Sample</title>
@@ -13,4 +13,4 @@
       </content>
     </section>
   </developerConceptualDocument>
-</topic>
+</topic>