docs(showcase): add volta.net

Author: benjamincanac

docs/content/showcase.yml

@@ -73,6 +73,8 @@ items:
     url: https://tresjs.org/
   - name: Uneed
     url: https://uneed.best/
+  - name: Volta
+    url: https://volta.net/
   - name: Wiredash
     url: https://wiredash.com/
   - name: Zielgestalt