Fix build error

TomWFox · web-flow · commit 8799df0da2c1 · 2019-04-15T20:12:53.000+01:00
diff --git a/arduino.md b/arduino.md
@@ -16,7 +16,6 @@ sections:
 - "arduino/push-notifications.md"
 - "arduino/analytics.md"
 - "arduino/cloud-code.md"
-- "arduino/sample-app.md"
 - "common/errors.md"
 
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