Document how a cluster admin assigns a developer the correct permissions to edit alert routing in user-workload monitoring. This new content should be similar to https://docs.openshift.com/container-platform/4.9/monitoring/enabling-monitoring-for-user-defined-projects.html#granting-users-permission-to-monitor-user-defined-projects_enabling-monitoring-for-user-defined-projects and should appear in the AlertmanagerConfigCRD configuration instructions.

From the linked dev issue
In CMO,  we have the existing [monitoring-edit|https://github.com/openshift/cluster-monitoring-operator/blob/26055d081b12fd1909fb626a3df291f8b62635dd/assets/cluster-monitoring-operator/monitoring-edit-cluster-role.yaml ] role that allows cluster admins to grant users permissions to edit their service/pod monitors and rules.

With the addition of the [alerting enhancement|https://github.com/openshift/enhancements/pull/937 ]  we should create a similar role which caters fo alertmanagerconfigs