Add reference to worker page

Author: wrjlewis

docs/SUMMARY.md

@@ -33,6 +33,7 @@
     - [`database`](./reference/cli/database.md)
     - [`manage`](./reference/cli/manage.md)
     - [`server`](./reference/cli/server.md)
+    - [`worker`](./reference/cli/worker.md)
     - [`templates`](./reference/cli/templates.md)
     - [`doctor`](./reference/cli/doctor.md)