Document defaultTolerations

Author: Rishit-dagli

content/en/docs/reference/labels-annotations-taints/_index.md

@@ -455,6 +455,12 @@ The presence of this annotation on a Job indicates that the control plane is
 [tracking the Job status using finalizers](/docs/concepts/workloads/controllers/job/#job-tracking-with-finalizers).
 You should **not** manually add or remove this annotation.
 
+### scheduler.alpha.kubernetes.io/defaultTolerations {#scheduleralphakubernetesio-defaulttolerations}
+
+Used on: Namespace
+
+This annotation requires the [PodTolerationRestriction](/docs/reference/access-authn-authz/admission-controllers/#podtolerationrestriction) admission  controller to be enabled. This annotation key allows assigning tolerations to a namespace and any new pods created in this namespace would get this toleration.
+
 ### scheduler.alpha.kubernetes.io/preferAvoidPods (deprecated) {#scheduleralphakubernetesio-preferavoidpods}
 
 Used on: Nodes