add uis-{staff,social} lists to on-boarding checklist

Closes #26

docs/workflow/onboarding.md

@@ -18,6 +18,8 @@ onboard a new member to the DevOps team.
     * Re-encrypt [docs repo's ansible vault password](https://gitlab.developers.cam.ac.uk/uis/devops/docs/general/blob/master/secrets/secrets.password.asc)
     * _Re-encrypt other repos' ansible vault passwords on an "as needed" basis_
 * Add public SSH key to [ansible add-devops-users role](https://gitlab.developers.cam.ac.uk/uis/devops/infra/ansible-roles/tree/master/roles/devops-ssh-users)
+* Get new member to visit https://lists.cam.ac.uk/mailman/listinfo/uis-staff and request membership. Follow up with email to uis-staff-owner@lists.cam.ac.uk explaining who new hire is.
+* If new member desires, get them to visit https://lists.cam.ac.uk/mailman/listinfo/uis-social and sign themselves up to the social list. No approval is required for this.
 
 If working on Gitlab deployment and/or MWSv3: