docs: PDBs for all pods, require spread

[devin-ai-integration]

Changes

This PR improves the high availability and deployment strategy of the docs deployment by:

1. Making pod anti-affinity required instead of preferred:

   • Changes preferredDuringSchedulingIgnoredDuringExecution to requiredDuringSchedulingIgnoredDuringExecution
   • Forces pods to be scheduled on different nodes for true HA
   • Pods will stay in Pending if spreading is not possible

2. Documenting existing PodDisruptionBudget (PDB) configuration:

   • Documents existing minAvailable: 1 setting that ensures at least one replica is always available
   • Protects against voluntary disruptions like node drains
   • Maintains existing PDB configuration for high availability

3. Adding explicit RollingUpdate strategy:

   • Configures maxSurge: 1 and maxUnavailable: 1
   • Ensures controlled rolling updates of deployments
   • Maintains service availability during updates

Link to Devin run: https://app.devin.ai/sessions/9e6ed5a722aa40b1b3ca0844542981ca

[devin-ai-integration]

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[github-actions]

Hugo yielded some warnings. Please check whether they require action.

WARN  Template shortcodes/autoscaling_supported_versions.html is unused, source file /home/runner/work/docs/docs/src/layouts/shortcodes/autoscaling_supported_versions.html

[lyind]

The error message from push-to-app-catalog is:

helm/docs-app/templates/deployment.yaml: (object: default/docs-app apps/v1, Kind=Deployment) anti-affinity's topology key does not match "" (check: no-anti-affinity, remediation: Specify anti-affinity in your pod specification to ensure that the orchestrator attempts to schedule replicas on different nodes. Using podAntiAffinity, specify a labelSelector that matches pods for the deployment, and set the topologyKey to kubernetes.io/hostname. Refer to https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#inter-pod-affinity-and-anti-affinity for details.)

[lyind]

Indentation error, otherwise looks fine.

[marians]

Thank you!

[pipo02mix]

Where has the bot documented it?

[lyind]

Where has the bot documented it?

Documented what? The changes by this PR?

I couldn't find a CHANGELOG.md in the repositories root, so dropped the changelog entries. 🤷

The changelog entries:

### Added

- Use `requiredDuringSchedulingIgnoredDuringExecution` for `podAntiAffinity`
- Add `PodDisruptionBudget` (PDB) for all deployments
- Add `RollingUpdate` strategy with `maxSurge: 1` and `maxUnavailable: 1`

[pipo02mix]

From the top messages with the changes made

[lyind]

Devin initially wrote the CHANGELOG entries in two different places, even creating a new CHANGELOG.md for the repository.

I told him this in one of the reviews: #2437 (comment)