Add deployment badge

README.md

@@ -2,6 +2,7 @@
 
 # Ray Optics Simulation
 [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.6386611.svg)](https://doi.org/10.5281/zenodo.6386611)
+[![Deploy to GitHub Pages](https://github.com/ricktu288/ray-optics/actions/workflows/deploy.yml/badge.svg)](https://github.com/ricktu288/ray-optics/actions/workflows/deploy.yml)
 
 A web app for creating and simulating 2D geometric optical scenes. Our goal is to make it easy for students to build physical intuition by "playing around", for teachers to do dynamical demonstrations, and at the same time also include tools for more advanced usage.
 
@@ -125,4 +126,4 @@ Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
-limitations under the License.
+limitations under the License.