Update docs workflow to use numpy-type documentation formatting

Author: Dashadower

.github/workflows/update_docs.yml

@@ -21,7 +21,7 @@ jobs:
         pip install pdoc
     - name: Run pdoc and commit
       run: |
-        pdoc --math -o docs stanify/
+        pdoc --math --docformat numpy -o docs stanify/
     - uses: EndBug/add-and-commit@v7
       with:
         default_author: github_actions