README: mention status badges

mvdan · mvdan · commit 5f1bff4f1263 · 2021-03-16T20:05:29.000+01:00
Since this question has come up a few times in the past, and badges are pretty commonly used. Fixes #19.
diff --git a/README.md b/README.md
@@ -30,7 +30,7 @@ jobs:
 ## Summary
 
 Each workflow file has a number of jobs, which get run `on` specified events,
-and run concurrently with each other.
+and run concurrently with each other. You can have workflow [status badges](https://docs.github.com/en/actions/managing-workflow-runs/adding-a-workflow-status-badge).
 
 Each `job` runs on a configuration `matrix`. For example, we can test two major
 Go versions on three operating systems.
