Invalid downstream documentation for PVC strategies

In the downstream documentation `4.3. Configuring storage strategies` referes to 

 which is incorrect

https://access.redhat.com/documentation/en-us/red_hat_codeready_workspaces/2.12/html/installation_guide/configuring-che_crw#storage-strategies-for-codeready-workspaces-workspaces_crw

The docs from upstream were not properly downstreamed - https://www.eclipse.org/che/docs/che-7/installation-guide/configuring-storage-strategies/

the common strategy should be the default one