Explicitly state that the default value for performanceprofile.spec.workloadHints.realTime is true

The default value for performanceprofile.spec.workloadHints.realTime is true, whereas it is false for highPowerConsumption and perPodPowerManagement

Make it clear to customers that realTime's default is true in the following 2 pages:

https://docs.openshift.com/container-platform/4.12/scalability_and_performance/cnf-low-latency-tuning.html#cnf-understanding-workload-hints_cnf-master
https://docs.openshift.com/container-platform/4.12/rest_api/node_apis/performanceprofile-performance-openshift-io-v2.html#spec-workloadhints