Make vue_shared danger message more concise

danger/vue_shared_documentation/Dangerfile

 # frozen_string_literal: true
 
+def has_matching_story?(file)
+  File.file?(file.dup.sub!(/\.vue$/, '.stories.js'))
+end
+
 def get_vue_shared_files(files)
   files.select do |file|
     file.end_with?('.vue') &&
       file.include?('vue_shared/') &&
-      !File.file?(file.dup.sub!(/\.vue$/, '.stories.js'))
+      !has_matching_story?(file)
   end
 end
 
@@ -12,14 +16,7 @@ vue_shared_candidates = get_vue_shared_files(helper.all_changed_files)
 
 return if vue_shared_candidates.empty?
 
-warn 'This merge request changed undocumented Vue components in `vue_shared/`. Please consider [adding documention](https://docs.gitlab.com/ce/development/fe_guide/storybook).'
-
-if helper.ci?
-  markdown(<<~MARKDOWN)
-    ## Undocumented Vue components
+documentation_url = 'https://docs.gitlab.com/ce/development/fe_guide/storybook'
+file_list = "- #{vue_shared_candidates.map { |path| "`#{path}`" }.join("\n- ")}"
 
-    The following Vue components don't have associated stories. Please consider [creating them](https://docs.gitlab.com/ce/development/fe_guide/storybook):
-
-    * #{vue_shared_candidates.map { |path| "`#{path}`" }.join("\n* ")}
-  MARKDOWN
-end
+warn "This merge request changed undocumented Vue components in `vue_shared/`. Please consider [creating Stories](#{documentation_url}) for these components:\n#{file_list}"