From OpenShift 4.4 on the built-in SCCs will be managed and thus
you cannot any longer mutate them by adding user. The proper way
is either to copy an existing SCC or use RBAC to access them.

This updates the documentation for the RBAC approach.
Signed-off-by: kmova <kiran.mova@mayadata.io>
(cherry picked from commit 92508da2ff6f629c0467239762b7c8ccce099dc3)