add upgrade note

kimchy · kimchy · commit a52d28fe4442 · 2011-04-24T00:17:51.000+03:00
diff --git a/blog/_posts/2011-04-23-0.16.0-released.textile b/blog/_posts/2011-04-23-0.16.0-released.textile
@@ -13,3 +13,7 @@ p. Features/enhancements include the ability to update many more index level set
 p. Many bugs have also been fix, with several critical ones revolving around possible data loss. Its highly recommended to upgrade.
 
 p. All changes are listed in the "0.16.0 download page":/download/2011/04/23/0.16.0.html.
+
+h1. Upgrade Notes
+
+p. The @_id@ field is no longer indexed by default. No functionality is lost by it, but, if the @_id@ field was used in term/terms query/filters, it should be replaced with the new ids query/filter. The issue explaining it is "here":https://github.com/elasticsearch/elasticsearch/issues/868.
