Resolve "Align recognized markdown extensions with file icon"

app/assets/javascripts/vue_shared/components/file_icon/file_icon_map.js

@@ -9,6 +9,12 @@ const fileExtensionIcons = {
   'md.rendered': 'markdown',
   markdown: 'markdown',
   'markdown.rendered': 'markdown',
+  mdown: 'markdown',
+  'mdown.rendered': 'markdown',
+  mkd: 'markdown',
+  'mkd.rendered': 'markdown',
+  mkdn: 'markdown',
+  'mkdn.rendered': 'markdown',
   rst: 'markdown',
   blink: 'blink',
   css: 'css',

changelogs/unreleased/257198-align-recognized-markdown-extensions-with-file-icon.yml

+---
+title: Add markdown icon to more file extensions
+merge_request: 43479
+author:
+type: fixed