Updated the NEWS file for 1.2.6 changes.

This commit was SVN r17697.

NEWS

@@ -92,8 +92,10 @@ Trunk (not on release branches yet)
   --> Expected: 1.3
 
 
-1.2.6 (not released yet, if ever)
+1.2.6 (not released yet)
 -----
+
+- Added shared contexts support to PSM MTL.
 - Added pml_ob1_use_early_completion MCA parameter to allow users
   to turn off the OB1 early completion semantic and avoid "stall"
   problems seen on InfiniBand in some cases.  See ticket #1224.