document pipeline value pipeline.event.github.pull_request.merged (#9601)

* Update github-trigger-event-options.adoc

* Update pipeline-values.adoc

Author: BeFunes

docs/guides/modules/ROOT/partials/pipelines-and-triggers/pipeline-values.adoc

@@ -421,6 +421,13 @@ a|  * GitLab: push, merge request
 | image:guides:ROOT:icons/check.svg[check icon, role="no-border"]
 | image:guides:ROOT:icons/cancel.svg[cancel icon, role="no-border"]
 
+| `pipeline.event.github.pull_request.merged`
+| GitHub App
+| Boolean
+| A boolean value indicating whether the pull request is has been merged. Only populated for pipelines triggered xref:guides:orchestrate:github-trigger-event-options.adoc#supported-trigger-options[by pull request events] (`pipeline.event.name = "pull_request"`).
+| image:guides:ROOT:icons/check.svg[check icon, role="no-border"]
+| image:guides:ROOT:icons/cancel.svg[cancel icon, role="no-border"]
+
 | `pipeline.deploy.component_name`
 | GitHub App
 | String

docs/guides/modules/orchestrate/pages/github-trigger-event-options.adoc

@@ -113,6 +113,7 @@ workflows:
 
 * `pipeline.event.github.pull_request.title`: the title of the pull request.
 * `pipeline.event.github.pull_request.number`: the numeric identifier of the pull request.
+* `pipeline.event.github.pull_request.merged`: a boolean that indicates whether the PR was merged or not. 
 
 These values are extracted directly from the GitHub event payload. The part after prefix `pipeline.event.github.*` matches the corresponding field in the pull request event structure described in link:https://docs.github.com/en/webhooks/webhook-events-and-payloads#pull_request[the GitHub docs].