Update single_stats_custom_dashboard.yml

.gitlab/dashboards/single_stats_custom_dashboard.yml

@@ -5,6 +5,9 @@ panel_groups:
       - title: Prometheus
         type: single-stat
         max_value: 120
+        y_axis:
+          format: 'percent'
+          precision: 2
         metrics:
           - id: single_stat_offset
             query: 'max(go_memstats_alloc_bytes{job="prometheus"}) / 1024 /1024'