bug: incorrect default chart value

[maxisam]

Describe the bug:

logging-operator/charts/logging-operator/values.yaml

Line 202 in 2f12207

nodeAgents: {}

this should be [] instead of {}

Expected behaviour:
A concise description of what you expected to happen.

Steps to reproduce the bug:
Steps to reproduce the bug should be clear and easily reproducible to help people
gain an understanding of the problem.

Additional context:
Add any other context about the problem here.

Environment details:

• Kubernetes version (e.g. v1.15.2):
• Cloud-provider/provisioner (e.g. AKS, GKE, EKS, PKE etc):
• logging-operator version (e.g. 2.1.1):
• Install method (e.g. helm or static manifests):
• Logs from the misbehaving component (and any other relevant logs):
• Resource definition (possibly in YAML format) that caused the issue, without sensitive data:

/kind bug

[pepov]

this will be removed in a future release