Update github-trigger-event-options.adoc (#9535)

Author: BeFunes

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

@@ -50,6 +50,7 @@ GitHub App triggers allow you to define the work to do (pipeline) when an event
 * *PR opened or pushed to, default branch and tag pushes*: Trigger a pipeline on pushes to a branch for which there is an open Pull Request (PR), when a PR is opened, pushes to any tag, and pushes to the default branch. This applies also if the PR is re-opened after being closed.
 * *PR opened*: Trigger a pipeline when a PR is opened. This applies also if the PR has been opened in draft. It does not apply if the PR is closed and then re-opened. See the link:https://docs.github.com/en/webhooks/webhook-events-and-payloads?actionType=opened#pull_request[GitHub docs for the pull request opened event].
 * *PR merged*: Trigger a pipeline when a PR is merged only. See the link:https://docs.github.com/en/webhooks/webhook-events-and-payloads?actionType=closed#pull_request[GitHub docs for pull request closed].
+* *PR merged or closed*: Trigger a pipeline when a PR is merged or closed. When this option is selected, pipelines will run by default on the _base_ branch on the pull request, not on the _head_ branch.
 * *PR marked ready for review*: Trigger a pipeline when a PR is taken out of draft mode and marked ready for review. See the link:https://docs.github.com/en/webhooks/webhook-events-and-payloads?actionType=review_requested#pull_request[GitHub docs for pull request review requested].
 * *"run-ci" label added to PR*: Trigger a pipeline when a label "run-ci" is added to a PR. See the link:https://docs.github.com/en/webhooks/webhook-events-and-payloads?actionType=labeled#pull_request[GitHub docs for pull request labelled].
 * *Pushes to open non-draft PRs*: Trigger a pipeline when there is a push to a branch with an open PR that is not in draft mode.