Add level four heading to text style dropdown

Changelog: changed

app/assets/javascripts/content_editor/constants.js

@@ -28,6 +28,12 @@ export const TEXT_STYLE_DROPDOWN_ITEMS = [
     commandParams: { level: 3 },
     label: __('Heading 3'),
   },
+  {
+    contentType: 'heading',
+    editorCommand: 'setHeading',
+    commandParams: { level: 4 },
+    label: __('Heading 4'),
+  },
   {
     contentType: 'paragraph',
     editorCommand: 'setParagraph',

locale/gitlab.pot

@@ -16297,6 +16297,9 @@ msgstr ""
 msgid "Heading 3"
 msgstr ""
 
+msgid "Heading 4"
+msgstr ""
+
 msgid "Headings"
 msgstr ""