[S2GRAPH-231] Change the GraphQL type name to a valid string.

JIRA:
  [S2GRAPH-231] https://issues.apache.org/jira/browse/S2GRAPH-231

Pull Request:
  Closes #180

Author
  daewon <daewon@apache.org>
diff --git a/CHANGES b/CHANGES
index da32f18..0595ad5 100644
--- a/CHANGES
+++ b/CHANGES
@@ -83,6 +83,7 @@
     * [S2GRAPH-214] - Add REAME for movielens examples
     * [S2GRAPH-216] - Provide a transform directive in the GraphQL query result.
     * [S2GRAPH-221] - Unify configurations for bulk and mutate in S2GraphSink.
+    * [S2GRAPH-231] - Change the GraphQL type name to a valid string.
 
 ** New Feature
     * [S2GRAPH-123] - Support different index on out/in direction.