Fix mkdocs build output path for Pages artifact

Author: sletz

.github/workflows/docs.yml

@@ -33,7 +33,8 @@ jobs:
         run: make -C doc md index
 
       - name: Build site
-        run: mkdocs build -f doc/mkdocs.yml -d site
+        working-directory: doc
+        run: mkdocs build -f mkdocs.yml -d ../site
 
       - uses: actions/configure-pages@v5