md5 dashboard name

Author: gotjosh

cortex-mixin/dashboards/alertmanager.libsonnet

@@ -3,7 +3,7 @@ local utils = import 'mixin-utils/utils.libsonnet';
 (import 'dashboard-utils.libsonnet') {
 
   'alertmanager.json':
-    $.dashboard('Cortex / Alertmanager')
+    $.dashboard('Cortex / Alertmanager') + { uid: std.md5('alertmanager.json') })
     .addClusterSelectorTemplates()
     .addRow(
       ($.row('Headlines') + {