Fence block as yml

diff --git a/docs/tutorial/testing-on-headless-ci.md b/docs/tutorial/testing-on-headless-ci.md
index 5e75235..343d2d2 100644 (file)
--- a/docs/tutorial/testing-on-headless-ci.md
+++ b/docs/tutorial/testing-on-headless-ci.md
@@ -34,7 +34,7 @@ xvfb-maybe electron-mocha ./test/*.js
 
 On Travis, your `.travis.yml` should look roughly like this:
 
-```
+```yml
 addons:
   apt:
     packages: