add pod generation to docs

content/en/docs/concepts/workloads/pods/_index.md

@@ -226,9 +226,13 @@ like
 have some limitations:
 
 - Most of the metadata about a Pod is immutable. For example, you cannot
-  change the `namespace`, `name`, `uid`, or `creationTimestamp` fields;
-  the `generation` field is unique. It only accepts updates that increment the
-  field's current value.
+  change the `namespace`, `name`, `uid`, or `creationTimestamp` fields.
+  - The `generation` field is unique. It will be automatically set by the
+    system such that new pods have a `generation` of 1, and every update to
+    mutable fields in the pod's spec will increment the `generation` by 1. If the
+    alpha feature gate PodObservedGenerationTracking is set, the
+    pod's `status.observedGeneration` will reflect the `metadata.generation` of
+    the pod at the point that the pod status is being reported.
 - If the `metadata.deletionTimestamp` is set, no new entry can be added to the
   `metadata.finalizers` list.
 - Pod updates may not change fields other than `spec.containers[*].image`,

content/en/docs/reference/command-line-tools-reference/feature-gates/PodObservedGenerationTracking.md

@@ -0,0 +1,13 @@
+---
+title: PodObservedGenerationTracking
+content_type: feature_gate
+_build:
+  list: never
+  render: false
+
+stages:
+  - stage: alpha
+    defaultValue: false
+    fromVersion: "1.33"
+---
+Enables the kubelet to set `observedGeneration` in the pod status and other components to set `observedGeneration` in pod conditions to reflect the `metadata.generation` of the pod at the time that the status or condition is being recorded.

content/en/docs/reference/command-line-tools-reference/kubelet.md

@@ -449,6 +449,7 @@ PodLifecycleSleepAction=true|false (BETA - default=true)<br/>
 PodLifecycleSleepActionAllowZero=true|false (ALPHA - default=false)<br/>
 PodLogsQuerySplitStreams=true|false (ALPHA - default=false)<br/>
 PodReadyToStartContainersCondition=true|false (BETA - default=true)<br/>
+PodObservedGenerationTracking=true|false (ALPHA - default=false)<br/>
 PortForwardWebsockets=true|false (BETA - default=true)<br/>
 ProcMountType=true|false (BETA - default=true)<br/>
 QOSReserved=true|false (ALPHA - default=false)<br/>