update CHANGES.txt to move HADOOP-11247 to 2.6

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -378,8 +378,6 @@ Release 2.7.0 - UNRELEASED
     HADOOP-11186. documentation should talk about
     hadoop.htrace.spanreceiver.classes, not hadoop.trace.spanreceiver.classes (cmccabe)
 
-    HADOOP-11247. Fix a couple javac warnings in NFS. (Brandon Li via wheat9)
-
 Release 2.6.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES
@@ -684,6 +682,7 @@ Release 2.6.0 - UNRELEASED
     HADOOP-11195. Move Id-Name mapping in NFS to the hadoop-common area for
     better maintenance (Yongjun Zhang via brandonli)
 
+    HADOOP-11247. Fix a couple javac warnings in NFS. (Brandon Li via wheat9)
 
   BUG FIXES