Add metric to docs

Signed-off-by: Omer Aplatony <omerap12@gmail.com>

Author: omerap12

vertical-pod-autoscaler/docs/features.md

@@ -126,4 +126,5 @@ VPA provides metrics to track in-place update operations:
 * `vpa_in_place_updatable_pods_total`: Number of pods matching in-place update criteria
 * `vpa_in_place_updated_pods_total`: Number of pods successfully updated in-place
 * `vpa_vpas_with_in_place_updatable_pods_total`: Number of VPAs with pods eligible for in-place updates
-* `vpa_vpas_with_in_place_updated_pods_total`: Number of VPAs with successfully in-place updated pods
+* `vpa_vpas_with_in_place_updated_pods_total`: Number of VPAs with successfully in-place updated pods
+* `vpa_updater_failed_in_place_update_attempts_total`: Number of failed attempts to update pods in-place.