docs: add callout plugin (#119)

.github/workflows/deploy_docs.yaml

@@ -24,7 +24,11 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install mkdocs mkdocs-material mkdocs-include-markdown-plugin
+        pip install \
+          mkdocs \
+          mkdocs-callouts \
+          mkdocs-include-markdown-plugin \
+          mkdocs-material
 
     - name: Build the documentation
       run: mkdocs build