chore: Add clo monitor exemption for artifact hub (open-telemetry#1491)

This defines a .clomonitor.yml file which is used by [clo
monitor](https://clomonitor.io/projects/cncf/open-telemetry).

This file contains an exemption for artifact hub as artifact's produced
by this library are not supported by artifact hub. By including the
exemption we can improve the score for this project and the
organisation. File contents have been copied from other repos where the
exemption has been applied.

Author: thompson-tomo

.clomonitor.yml

@@ -0,0 +1,4 @@
+# see https://github.com/cncf/clomonitor/blob/main/docs/checks.md#exemptions
+exemptions:
+  - check: artifacthub_badge
+    reason: "Artifact Hub doesn't support go or rust packages"