Add milestones to dashboard dev docs images

...age_group_observability/dashboards/error_budget_detail.md

...y/dashboards/img/error_budget_detail_7d_budget_v14_10.png

...ability/dashboards/img/error_budget_detail_sli_v14_10.png

...mg/error_budget_detail_stage_group_aggregation_v14_10.png

...shboards/img/stage_group_dashboards_28d_budget_v14_10.png

...shboards/img/stage_group_dashboards_annotation_v14_10.png

.../dashboards/img/stage_group_dashboards_debug_1_v14_10.png

.../dashboards/img/stage_group_dashboards_debug_2_v14_10.png

.../dashboards/img/stage_group_dashboards_debug_3_v14_10.png

.../dashboards/img/stage_group_dashboards_filters_v14_10.png

.../dashboards/img/stage_group_dashboards_metrics_v14_10.png

.../img/stage_group_dashboards_time_customization_v14_10.png

...hboards/img/stage_group_dashboards_time_filter_v14_10.png

...development/stage_group_observability/dashboards/index.md

...e_group_observability/dashboards/stage_group_dashboard.md

...ty/img/stage_group_dashboards_error_attribution_v14_1.png

...y/img/stage_group_dashboards_service_sli_detail_v14_1.png

doc/development/stage_group_observability/index.md