Fixing linting

Change-Id: Iaefc1062efbbc11c0f12e02237892023dc19966e
diff --git a/developer/README.md b/developer/README.md
index e2c0350..180629e 100644
--- a/developer/README.md
+++ b/developer/README.md
@@ -11,6 +11,6 @@
 
 Usage:
 
-```
+```shell
 python imagebuilder.py -f ../../helm-charts/examples/filter-images.yaml -x
 ```