Add oss-fuzz fuzzing status badge to README (#767)

diff --git a/README.md b/README.md
index 5da2743..d4db09d 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@
 
 [![TravisCI Build Status](https://travis-ci.org/google/brotli.svg?branch=master)](https://travis-ci.org/google/brotli)
 [![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/github/google/brotli?branch=master&svg=true)](https://ci.appveyor.com/project/szabadka/brotli)
+[![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/brotli.svg)](https://oss-fuzz-build-logs.storage.googleapis.com/index.html#brotli)
 
 ### Build instructions