chore: add badges

Author: ww24

README.md

@@ -1,4 +1,11 @@
 scheduler
 ===
 
+[![Go Reference][go-dev-img]][go-dev-url]
+![Test][github-actions-img]
+
 Scheduler manages scheduled tasks using CloudTasks.
+
+[github-actions-img]: https://github.com/go-oss/scheduler/workflows/test/badge.svg?branch=master
+[go-dev-img]: https://pkg.go.dev/badge/github.com/go-oss/scheduler.svg
+[go-dev-url]: https://pkg.go.dev/github.com/go-oss/scheduler