Doc link:

https://access.redhat.com/documentation/en-us/red_hat_advanced_cluster_management_for_kubernetes/2.8/html-single/clusters/index#create-cluster-configuring-nodeselector-tolerations

Doc section:

1.5.15.2. Optional: Configuring the klusterlet to run on specific nodes

Doc improvement suggestion:

The annotations open-cluster-management/nodeSelector and open-cluster-management/tolerations must not be escaped. In the given example a working configuration would be:
apiVersion: cluster.open-cluster-management.io/v1
kind: ManagedCluster
metadata:
annotations:
open-cluster-management/nodeSelector: '

'
open-cluster-management/tolerations: '[

]'