docs: mention QuantumCumulants.jl (#15)

Author: oameye

README.md

@@ -8,25 +8,25 @@
 [![Aqua QA](https://raw.githubusercontent.com/JuliaTesting/Aqua.jl/master/badge.svg)](https://github.com/JuliaTesting/Aqua.jl)
 [![jet](https://img.shields.io/badge/%F0%9F%9B%A9%EF%B8%8F_tested_with-JET.jl-233f9a)](https://github.com/aviatesk/JET.jl)
 
-A Julia package for symbolic manipulation and algebraic computation with second quantized operators.  
-SecondQuantizedAlgebra.jl provides a flexible framework for working with creation and annihilation operators, commutation relations, and algebraic expressions common in quantum many-body theory and quantum optics.
-
-## Features
+A Julia package for symbolic manipulation and algebraic computation with second quantized operators. SecondQuantizedAlgebra.jl provides a flexible framework for working with creation and annihilation operators, commutation relations, and algebraic expressions common in quantum many-body theory and quantum optics.
 
+The package provides:
 - Symbolic representation of bosonic fock creation and annihilation operators
 - Automatic (anti-)commutation relation handling
 - Algebraic simplification and normal ordering
 - Support for atom and spin operators
 - Extensible for custom operator types
 
-## Installation
+The code was refactored out of [QuantumCumulants.jl](https://github.com/qojulia/QuantumCumulants.jl).
+
+### Installation
 
 Install with Julia's package manager:
 ```julia
 pkg> add SecondQuantizedAlgebra
 ```
 
-## Usage
+### Usage
 
 ```julia
 using SecondQuantizedAlgebra
@@ -55,4 +55,4 @@ Contributions and suggestions are welcome! Please open issues or pull requests o
 
 ## License
 
-This project is licensed under the MIT License.
+This project is licensed under the MIT License.