updated README and CI workflow

.github/workflows/pip.yaml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [windows-latest, ubuntu-latest]
+        os: [windows-latest, macos-latest, ubuntu-latest]
         python-version: ["3.8", "3.9", "3.10", "3.11"]
 
     steps:
@@ -22,6 +22,7 @@ jobs:
       uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
+
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

README.md

@@ -94,3 +94,22 @@ pip install "path to interface" --config-settings=cmake.build-type="DEBUG"
 ```
 Then compile your C++ problem description in debug mode and use a suitable debugger. 
 Using the `Python C++ Debugger` extensions for VS Code is a reliable way to debug Python and C++ code.
+
+## Citing
+
+If you are using GRAMPC in your work, please cite 
+```
+@Article{,
+  author   = {Englert, Tobias and Völz, Andreas and Mesmer, Felix and Rhein, Sönke and Graichen, Knut},
+  title    = {A software framework for embedded nonlinear model predictive control using a gradient-based augmented Lagrangian approach (GRAMPC)},
+  doi      = {10.1007/s11081-018-9417-2},
+  issn     = {1573-2924},
+  number   = {3},
+  pages    = {769--809},
+  url      = {https://doi.org/10.1007/s11081-018-9417-2},
+  volume   = {20},
+  journal  = {Optimization and Engineering},
+  refid    = {Englert2019},
+  year     = {2019},
+}
+```