Add a section for deployment statuses describing data retention plan (#62262)

Co-authored-by: Isaac Brown <101839405+isaacmbrown@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: 3 people

content/rest/deployments/statuses.md

@@ -12,6 +12,16 @@ category:
   - Automate CI/CD workflows
 ---
 
+## About deployment statuses
 
+Deployment statuses allow external services to mark deployments with an `error`, `failure`, `inactive`, `in_progress`, `queued`, `pending`, or `success` state. Systems listening to [`deployment_status` events](/webhooks/webhook-events-and-payloads#deployment_status) can consume and respond to these statuses. A deployment status can also include an optional `description` and `log_url`.
+
+A deployment can accumulate multiple statuses over time as it progresses, for example from `pending` to `in_progress` to `success`. {% data variables.product.github %} tracks the most recent status for each deployment and uses it to display the deployment's current state.
+
+### Data retention
+
+{% data variables.product.github %} retains records of previous deployment statuses for **90 days**. Previous statuses older than 90 days are automatically deleted and are no longer returned by the REST API or GraphQL API.
+
+This retention policy applies to all deployment status endpoints, including [List deployment statuses](#list-deployment-statuses) and [Get a deployment status](#get-a-deployment-status). The current status of a deployment is not affected, because it is stored on the deployment itself and remains available regardless of the deployment's age.
 
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