Add CLE documentation

Author: Jefftree

content/en/docs/concepts/architecture/coordinated-leader-election.md

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+---
+reviewers:
+- jpbetz
+title: Coordinated Leader Election
+content_type: concept
+weight: 200
+---
+
+<!-- overview -->
+
+{{< feature-state feature_gate_name="CoordinatedLeaderElection" >}}
+
+Kubernetes {{< skew currentVersion >}} includes an alpha feature that allows
+components to deterministically select a leader via Coordinated Leader Election.
+This is useful to satisfy Kubernetes version skew during cluster upgrades.
+Currently, the only supported selection strategy is `OldestEmulationVersion`,
+preferring the leader with the lowest emulation version, followed by binary
+version, followed by creation timestamp.
+
+## Enabling Coordinated Leader Election
+
+Ensure that `CoordinatedLeaderElection` [feature
+gate](/docs/reference/command-line-tools-reference/feature-gates/) is enabled
+when you start the {{< glossary_tooltip text="API Server"
+term_id="kube-apiserver" >}}: and that the `coordination.k8s.io/v1alpha1` API is
+enabled.
+
+This can be done by setting `FEATURE_GATES="CoordinatedLeaderElection=true"` and
+`RUNTIME_CONFIG="coordination.k8s.io/v1alpha1=true"`.
+
+## Component Configuration
+
+With Coordinated Leader Election, components need to both run a LeaseCandidate
+and Lease goroutine (both found in client-go/pkg/leaderelection). Two components
+(kube-controller-manager and kube-scheduler) will automatically use coordinated
+leader election if enabled. Please refer to the example found in
+`k8s.io/cmd/kube-scheduler/app/server.go` on set up.
+
+The created LeaseCandidate object looks similar to below:
+
+```
+apiVersion: coordination.k8s.io/v1alpha1
+kind: LeaseCandidate
+metadata:
+  name: hostname_uuid
+  namespace: kube-system
+spec:
+  binaryVersion: 1.31.0
+  emulationVersion: 1.31.0
+  leaseName: kube-scheduler
+  preferredStrategies:
+  - OldestEmulationVersion
+  renewTime: "2024-07-30T03:45:18.325483Z"
+```
+
+Please refer to the documentation for LeaseCandidate for the full API details.

content/en/docs/reference/command-line-tools-reference/feature-gates/coordinated-leader-election.md

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+---
+title: CoordinatedLeaderElection
+content_type: feature_gate
+_build:
+  list: never
+  render: false
+
+stages:
+  - stage: alpha
+    defaultValue: false
+    fromVersion: "1.31"
+---
+Enables coordinated leader election for leases, deterministically
+managing the leader in leader elected components.