Further clarifications in the instructions for rendering content from…

… external repositories

pages/docs/docs-meta/docs-meta-overview.md

@@ -148,4 +148,6 @@ To render the fetched content on the website:
 2. In the same file, add an entry under the `defaults:` list, associating the subproject with some layout, sidebar, a path for the "Edit me" button, and more features.
 3. Remember to make the new pages discoverable, e.g., by adding them to some [sidebar](https://github.com/precice/precice.github.io/tree/master/_data/sidebars), or linking from another page.
 
+After you merge the pull request in the external repository, remember to change the brach in the submodule (step 2) and in the `_config.yml` (step 1). If you squash-and-merge the pull request, the commit you were pointing to will not exist anymore. The easiest workaround it to delete the `imported/my-project` folder and update the submodules again (remember to add, commit, and push). You can always check the `git diff` for the commit it will point the submodule to.
+
 To update the content, push to your repository and then [manually trigger the "update submodules" workflow](https://github.com/precice/precice.github.io/actions/workflows/update-submodules.yml). Alternatively, add a GitHub Actions workflows to your repository, to [update the website automatically](https://github.com/precice/tutorials/blob/master/.github/workflows/update-website.yml).