Clarify related MRs' condition for a security implementation issue

.gitlab/issue_templates/Security developer workflow.md

@@ -34,8 +34,12 @@ After your merge request has been approved according to our [approval guidelines
   - You can use the script `bin/secpick` instead of the following steps, to help you cherry-picking. See the [secpick documentation]
 - [ ] Create each MR targeting the stable branch `X-Y-stable`, using the [Security merge request template].
   - Every merge request will have its own set of to-dos, so make sure to complete those.
-- [ ]  On the `Related merge requests` section, ensure that **ONLY** `4` merge requests are associated: **ONLY** one targeting `master` and the `3` backports.
-  - [ ]  If there are more associated MRs, re-create another security issue and ensure there are only 4 merge requests associated with that one.
+- [ ]  On the `Related merge requests` section, ensure that **ONLY** `4` merge requests matching these conditions:
+  - From the security namespace (`gitlab-org/security`)
+  - Status is not `Closed`
+  - (Other MRs not matching these above conditions are acceptable)
+  - [ ] Among these `4` MRs, one targeting `master` and the `3` backports targeting stable branches.
+  - [ ] If there are more associated MRs, re-create another security issue and ensure there are only 4 merge requests associated with that one.
 - [ ] If this issue requires less than `4` merge requests, add the ~"reduced backports" label.
 
 ## Assigning to a release