Added some missing secrets for Airflow

All Submissions:

[YES] Have you added an explanation of what your changes do and why you'd like us to include them?
[YES] I have updated the documentation accordingly.
[YES] I have added tests to cover my changes.
[YES] All new and existing tests passed.
[YES] I have formatted the terraform code. (terraform fmt -recursive && go fmt ./...)

Adding in missing Airflow configuration information.