Added Squadcast to the list of Alertmanager webhook receiver (#1642)
Added Squadcast to the list of Alertmanager webhook receiver (#1642)

* Added Squadcast to the list of Alertmanager webhook receiver

Signed-off-by: Raghu <3260172cf68a6e6438ef182097ef4bd76169c572@squadcast.com>
prometheus/docs,prometheus/docs,prometheus/docs