Disclaimer required in the starting of Loki Documentation

We need to add a disclaimer in the documentation[0] about adding a group `cluster-admin` to make sure Loki does not return an Input size too long error

As per the design and code of Loki,clusteradmin user needs to be part of the group `cluster-admin` to make sure that if the sum of the total character of the namespace exceeds the limit of 5120 it does not return an error  Input size too long error

If there a group named `cluster-admin` does not exist, Create a new group and add `clusteradmin` users to that group.

Steps

$ oc adm groups new cluster-admin

$ oc adm groups add-users cluster-admin username

$ oc adm policy add-cluster-role-to-group cluster-admin cluster-admin