docs: clarify running privileged with selinux

The operator setting ROOK_HOSTPATH_REQUIRES_PRIVILEGED is expected to be true
when selinux is enabled, not just with openshift.

Signed-off-by: Travis Nielsen <tnielsen@redhat.com>

cluster/examples/kubernetes/ceph/operator-openshift.yaml

@@ -416,7 +416,7 @@ spec:
         - name: ROOK_DISCOVER_DEVICES_INTERVAL
           value: "60m"
         # Whether to start pods as privileged that mount a host path, which includes the Ceph mon and osd pods.
-        # This is necessary to workaround the anyuid issues when running on OpenShift.
+        # Set this to true if SELinux is enabled (e.g. OpenShift) to workaround the anyuid issues.
         # For more details see https://github.com/rook/rook/issues/1314#issuecomment-355799641
         - name: ROOK_HOSTPATH_REQUIRES_PRIVILEGED
           value: "true"

cluster/examples/kubernetes/ceph/operator.yaml

@@ -363,7 +363,7 @@ spec:
           value: "60m"
 
         # Whether to start pods as privileged that mount a host path, which includes the Ceph mon and osd pods.
-        # This is necessary to workaround the anyuid issues when running on OpenShift.
+        # Set this to true if SELinux is enabled (e.g. OpenShift) to workaround the anyuid issues.
         # For more details see https://github.com/rook/rook/issues/1314#issuecomment-355799641
         - name: ROOK_HOSTPATH_REQUIRES_PRIVILEGED
           value: "false"