link coverity status from README.md

README.md

diff --git a/README.md b/README.md
index fc13584..33b9114 100644
--- a/README.md
+++ b/README.md
@@ -38,3 +38,4 @@
 If you want to reach the authors in private, use <libzip@nih.at>.
 
 ![Travis Build Status](https://api.travis-ci.org/nih-at/libzip.svg?branch=master)
+![Coverity Status](https://scan.coverity.com/projects/127/badge.svg?flat=1)