Add CLOMonitor badge

Signed-off-by: Doug Davis <dug@microsoft.com>

Author: Doug Davis

README.md

@@ -4,6 +4,8 @@
 
 ![CloudEvents logo](https://github.com/cncf/artwork/blob/master/projects/cloudevents/horizontal/color/cloudevents-horizontal-color.png)
 
+[![CLOMonitor](https://img.shields.io/endpoint?url=https://clomonitor.io/api/projects/cncf/cloudevents/badge)](https://clomonitor.io/projects/cncf/cloudevents)
+
 Events are everywhere. However, event producers tend to describe events
 differently.