Specify security issue must be included on MR desc

Specify that GitLab security issue must be written down on the MR
description

.gitlab/merge_request_templates/Security Release.md

@@ -12,7 +12,7 @@ See [the general developer security release guidelines](https://gitlab.com/gitla
 
 ## Developer checklist
 
-- [ ] **Make sure this merge request mentions the [GitLab Security] issue it belongs to (i.e. `Related to <issue_id>`).**
+- [ ] **On "Related issues" section, write down the [GitLab Security] issue it belongs to (i.e. `Related to <issue_id>`).**
 - [ ] Merge request targets `master`, or `X-Y-stable` for backports.
 - [ ] Milestone is set for the version this merge request applies to. A closed milestone can be assigned via [quick actions].
 - [ ] Title of this merge request is the same as for all backports.