Update CHANGELOG.md

Author: ytdHuang

CHANGELOG.md

@@ -8,7 +8,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased](https://github.com/qutip/QuantumToolbox.jl/tree/main)
 
 - Add support of `QobjEvo` for `steadystate` (ODE solver only). ([#536])
-- Fix keyword argument handling for `SteadyStateODESolver`. ([#537])
+- Changes to `SteadyStateODESolver`. ([#537])
+  - Introduce the terminate tolerances for calculating `steadystate` (two new fields: `terminate_abstol = 1e-5` and `terminate_abstol = 1e-7`)
+  - Fix keyword argument handling for `SteadyStateODESolver`.
 
 ## [v0.34.1]
 Release date: 2025-08-23