docs(platformAutomerge): recommend setting required status checks (#16965)

docs/usage/configuration-options.md

@@ -1904,6 +1904,15 @@ If enabled Renovate will pin Docker images by means of their SHA256 digest and n
 
 ## platformAutomerge
 
+<!-- prettier-ignore -->
+!!! warning
+    Before you enable `platformAutomerge` you should enable your Git hosting platform's capabilities to enforce test passing before PR merge.
+    If you don't do this, the platform might merge Renovate PRs even if the repository's tests haven't started, are in still in progress, or possibly even when they have failed.
+    On GitHub this is called "Require status checks before merging", which you can find in the "Branch protection rules" section of the settings for your repository.
+    [GitHub docs, about protected branches](https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/defining-the-mergeability-of-pull-requests/about-protected-branches)
+    [GitHub docs, require status checks before merging](https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/defining-the-mergeability-of-pull-requests/about-protected-branches#require-status-checks-before-merging)
+    If you're using another platform, search their documentation for a similar feature.
+
 If you have enabled `automerge` and set `automergeType=pr` in the Renovate config, then you can also set `platformAutomerge` to `true` to speed up merging via the platform's native automerge functionality.
 
 Renovate tries platform-native automerge only when it initially creates the PR.