Add border top to Readme file header

app/views/projects/tree/_readme.html.haml

 - if readme.rich_viewer
   %article.file-holder.readme-holder{ id: 'readme', class: [("limited-width-container" unless fluid_layout), ("js-show-on-root" if vue_file_list_enabled?)] }
-    .js-file-title.file-title
+    .js-file-title.file-title-flex-parent
+      .file-header-content
         = blob_icon readme.mode, readme.name
         = link_to project_blob_path(@project, tree_join(@ref, readme.path)) do
           %strong

changelogs/unreleased/27025-add-border-top-in-readme.yml

+---
+title: Fix top border of README file header in file list
+merge_request: 21314
+author:
+type: fixed