Resolve "Update merge request template"

Closes #1084 (closed)

.gitlab/merge_request_templates/DEFAULT.md

@@ -3,6 +3,9 @@ that you:
 
 - [ ] Updated chart version number in `Chart.yaml`
 - [ ] Updated the `CHANGELOG.md`
-- [ ] Manually tested chart changes with the stackspin bootstrap script
+### Test in stackspin/stackspin (if applicable)
+
+If you made very big changes to the chart, you'll want to test whether the chart still works before releasing the new version. To do so, create an MR in the stackspin/stackspin repository, change `flux2/core/base/sources/nextcloud-helmrepository.yaml` to track the `unstable` helm repository, instead of `stable`, and change `flux2/apps/nextcloud/release.yaml` to this MRs chart version.
+
 - [ ] Created an MR in stackspin/stackspin that applies the changes from this MR
 - [ ] Tests in that MR in stackspin/stackspin succeed