update changelog

Author: TendonFFF

CHANGELOG.md

@@ -8,6 +8,7 @@ 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 for `OperatorKet` state input for `mesolve` and `smesolve`. ([#423])
+- Introduce `plot_fock_distribution` to plot the population of a state (ket, bra, or density matrix) in its basis (assumed to be Fock basis). ([#428])
 
 ## [v0.28.0]
 Release date: 2025-02-22
@@ -174,3 +175,4 @@ Release date: 2024-11-13
 [#420]: https://github.com/qutip/QuantumToolbox.jl/issues/420
 [#421]: https://github.com/qutip/QuantumToolbox.jl/issues/421
 [#423]: https://github.com/qutip/QuantumToolbox.jl/issues/423
+[#428]: https://github.com/qutip/QuantumToolbox.jl/issues/428