DocumentDBAttribute.ConnectionStringSetting not set correctly

[shadowmulder]

tried out example but during the test with curl
curl -d '{"key1":"value1", "key2":"value2"}' -H "Content-Type: application/json" -X POST https://http-crud-example.azurewebsites.net/api/api/?code=2BxWPc7MRxtSa9S1ku7/knw2aqDg1eiFClbugUA==

it ended in a missing property (same over web console)
Exception while executing function: Functions.create. Microsoft.Azure.WebJobs.Host: Unable to resolve app setting for property 'DocumentDBAttribute.ConnectionStringSetting'. Make sure the app setting exists and has a valid value. 2018-12-31T16:46:31.536 [Error] Function completed (Failure, Id=e7ac970f-4c11-429f-8ff8-4958896207b5, Duration=320ms)