Add the labels directly instead of just hinting

Grooming missed deliverable improvement

Following up https://gitlab.com/gitlab-org/gitlab-triage/issues/62 and !4 (merged) we have the following observations:

• ~~We want to exclude ~Documentation and development guidelines https://gitlab.com/gitlab-org/gitlab-ce/issues/48021#note_93871554~~
• ~~This has milestone %11.4 but also has missed:11.2 added manually, so the bot added missed-deliverable. But it seems to be a bit odd to me because the milestone is now moved to %11.4 https://gitlab.com/gitlab-org/gitlab-ce/issues/25990#note_93870897~~
• Update the comment to make it more clear: #26 (comment 94120523) -> !6 (merged)
• ~~[ ] Exclude ~"product discovery"~~
• Just add missed:x.xx directly.

I'll add items here when I got more