Add release notes for 1.2.6/1.2.7
Add release notes for 1.2.6/1.2.7

skob/alerta,guardian/alerta,skob/alerta,skob/alerta,0312birdzhang/alerta,mrkeng/alerta,guardian/alerta,0312birdzhang/alerta,mrkeng/alerta,guardian/alerta,guardian/alerta,0312birdzhang/alerta,mrkeng/alerta,mrkeng/alerta,skob/alerta