Fix example silence query parameter
Fix example silence query parameter

Signed-off-by: Marcel Hoegel <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@mclhgl.de>

GoogleCloudPlatform/alertmanager,GoogleCloudPlatform/alertmanager,GoogleCloudPlatform/alertmanager,prometheus/alertmanager,prometheus/alertmanager,GoogleCloudPlatform/alertmanager,prometheus/alertmanager,prometheus/alertmanager