[chore] Add OSS-Fuzz badge (#6817)

Author: pellared

README.md

@@ -4,6 +4,7 @@
 [![codecov.io](https://codecov.io/gh/open-telemetry/opentelemetry-go-contrib/coverage.svg?branch=main)](https://app.codecov.io/gh/open-telemetry/opentelemetry-go-contrib?branch=main)
 [![Docs](https://godoc.org/go.opentelemetry.io/contrib?status.svg)](https://pkg.go.dev/go.opentelemetry.io/contrib)
 [![Go Report Card](https://goreportcard.com/badge/go.opentelemetry.io/contrib)](https://goreportcard.com/report/go.opentelemetry.io/contrib)
+[![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/opentelemetry-go-contrib.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:opentelemetry-go-contrib)
 [![Slack](https://img.shields.io/badge/slack-@cncf/otel--go-brightgreen.svg?logo=slack)](https://cloud-native.slack.com/archives/C01NPAXACKT)
 
 Collection of 3rd-party packages for [OpenTelemetry-Go](https://github.com/open-telemetry/opentelemetry-go).