Kubernetes documentation enhancements

[greenaar]

Updated volume mount example to include both plugin and non-plugin based, as settings is incompatible with commands

Added a link to the Kubernetes PVC documentation, and a note about ReadWriteMany.

Added details around setting up prometheus monitoring where both prometheus and woodpecker are in the same cluster.

Included troubleshooting for prometheus failing to scrape metrics.

Added links and examples for serviceAccountName configuration.

[woodpecker-bot]

Deployment of preview was torn down

[6543]

CI failed ...