Improve message when promoting labels

Adds a note that an existing group label with the same title
would also be merged

app/assets/javascripts/pages/projects/labels/components/promote_label_modal.vue

@@ -37,7 +37,8 @@ export default {
     text() {
       return sprintf(
         s__(`Labels|Promoting %{labelTitle} will make it available for all projects inside %{groupName}.
-        Existing project labels with the same title will be merged. This action cannot be reversed.`),
+        Existing project labels with the same title will be merged. If a group label with the same title exists,
+        it will also be merged. This action cannot be reversed.`),
         {
           labelTitle: this.labelTitle,
           groupName: this.groupName,

changelogs/unreleased/212710-improve-message-when-promoting-labels.yml

+---
+title: Improve message when promoting project labels
+merge_request: 28265
+author:
+type: other

doc/user/project/labels.md

@@ -74,9 +74,14 @@ and selecting **Delete**.
 #### Promote a project label to a group label
 
 If you previously created a project label and now want to make it available for other
-projects within the same group, you can promote it to a group label. If other projects
-in the same group have a label with the same name, they will all be overwritten by
-the new group label.
+projects within the same group, you can promote it to a group label.
+
+If other projects in the same group have a label with the same title, they will all be
+merged with the new group label. If a group label with the same title exists, it will
+also be merged.
+
+All issues, merge requests, issue board lists, issue board filters, and label subscriptions
+with the old labels will be assigned to the new group label.
 
 WARNING: **Caution:**
 Promoting a label is a permanent action, and cannot be reversed.

locale/gitlab.pot

@@ -11587,7 +11587,7 @@ msgstr ""
 msgid "Labels|Promote Label"
 msgstr ""
 
-msgid "Labels|Promoting %{labelTitle} will make it available for all projects inside %{groupName}. Existing project labels with the same title will be merged. This action cannot be reversed."
+msgid "Labels|Promoting %{labelTitle} will make it available for all projects inside %{groupName}. Existing project labels with the same title will be merged. If a group label with the same title exists, it will also be merged. This action cannot be reversed."
 msgstr ""
 
 msgid "Labels|and %{count} more"