metrics docs: document image_garbage_collected_total metric

Signed-off-by: Peter Hunt <[email protected]>

content/en/docs/reference/instrumentation/metrics.md

@@ -1604,6 +1604,13 @@ Alpha metrics do not have any API guarantees. These metrics must be used at your
 	<div class="metric_help">Number of reconciliations of HPA controller. The label 'action' should be either 'scale_down', 'scale_up', or 'none'. Also, the label 'error' should be either 'spec', 'internal', or 'none'. Note that if both spec and internal errors happen during a reconciliation, the first one to occur is reported in `error` label.</div>
 	<ul>
 	<li><label class="metric_detail">Stability Level:</label><span class="metric_stability_level">ALPHA</span></li>
+	<li data-type="histogram"><label class="metric_detail">Type:</label> <span class="metric_type">Counter</span></li>
+	<li class="metric_labels_varying"><label class="metric_detail">Labels:</label><span class="metric_label">reason</span></li></ul>
+	</div><div class="metric" data-stability="alpha">
+	<div class="metric_name">image_garbage_collected_total</div>
+	<div class="metric_help">Total number of images garbage collected by the kubelet, whether through disk usage or image age.</div>
+	<ul>
+	<li><label class="metric_detail">Stability Level:</label><span class="metric_stability_level">ALPHA</span></li>
 	<li data-type="counter"><label class="metric_detail">Type:</label> <span class="metric_type">Counter</span></li>
 	<li class="metric_labels_varying"><label class="metric_detail">Labels:</label><span class="metric_label">action</span><span class="metric_label">error</span></li></ul>
 	</div><div class="metric" data-stability="alpha">