Fix yaml whitespace in plugin installation documentation example

[ptrbp]

Description

Minor fix for plugin installation using env vars documentation example.

name should be a child of secretRef.

Without the fix:

error: error validating "STDIN": error validating data: ValidationError(Grafana.spec.deployment.envFrom[0]): unknown field "name" in org.integreatly.v1alpha1.Grafana.spec.deployment.envFrom; if you choose to ignore these errors, turn validation off with --validate=false

Type of change

Documentation fix

Checklist

• This change requires a documentation update
• I have added tests that prove my fix is effective or that my feature works
• I have added a test case that will be used to verify my changes
• Verified independently on a cluster by reviewer

[hubeadmin]

Thank you, nice catch! we love it when the community catches things like this!