Added blurb for gpu-counters and SHS parameter change

Author: hagertnl

systems/frontier_user_guide.rst

@@ -3888,6 +3888,12 @@ If it is necessary to have bit-wise reproducible results from these libraries, i
 System Updates 
 ============== 
 
+2025-07-29
+----------
+On Tuesday, July 29, 2025, Frontier's Slingshot Host Software 12.0.1 was patched to adjust a parameter known to contribute to a recent regression in the performance of ``MPI_Alltoall`` at full-system scale (>8K nodes).
+Additionally, the ``--gpu-counters`` flag to ``sbatch`` was enabled by default for all jobs >1800 nodes.
+Please see `Software News <https://docs.olcf.ornl.gov/software/software-news.html>`_ for further information about this feature.
+
 2025-06-17
 ----------
 On Tuesday, June 17, 2025, Frontier's system software was upgraded.