fixed small typo
fixed small typo

Signed-off-by: Dominik Zalewski <394772b3b3f90e4d765f36eedc9c044fb67b3987@gmail.com>

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