Fix secret file mode bits example on JSON
Fix secret file mode bits example on JSON

I tested the example on YAML and, wrongly, asumed that JSON supported it too.

Fixes: https://github.com/kubernetes/kubernetes/issues/33162

rata/kubernetes.github.io,erictune/erictune.github.io,aidevops/kubernetes.github.io,erictune/erictune.github.io,aidevops/kubernetes.github.io,aidevops/kubernetes.github.io,aidevops/kubernetes.github.io,rata/kubernetes.github.io,aidevops/kubernetes.github.io,erictune/erictune.github.io,rata/kubernetes.github.io,erictune/erictune.github.io,rata/kubernetes.github.io,rata/kubernetes.github.io,erictune/erictune.github.io