GitHub issue: 

https://github.com/openshift/openshift-docs/issues/43227

The issue requster has already raised a PR with the changes. It needs to go through doc review and approval process to go live. 

Which section(s) is the issue in?

https://docs.openshift.com/container-platform/4.9/monitoring/configuring-the-monitoring-stack.html#configuring-the-monitoring-stack_configuring-the-monitoring-stack

What needs fixing?

yaml for the prometheus volume needs to be corrected. Incorrect spacing starting at "spec"...

data:
  config.yaml: |
    prometheusK8s: 
      volumeClaimTemplate:
       spec:
         storageClassName: fast
         volumeMode: Filesystem
         resources:
           requests:
             storage: 40Gi