Update empty state page of merge request 'changes' tab

app/assets/stylesheets/pages/merge_requests.scss

@@ -384,6 +384,12 @@
   }
 }
+.nothing-here-block {
+  img {
+    width: 230px;
+  }
+}
+
 .mr-list {
   .merge-request {
     padding: 10px  0 10px 15px;

app/views/projects/merge_requests/diffs/_diffs.html.haml

@@ -2,4 +2,12 @@
   = render 'projects/merge_requests/diffs/versions'
   = render "projects/diffs/diffs", diffs: @diffs, environment: @environment, merge_request: true
 - elsif @merge_request_diff.empty?
-  .nothing-here-block Nothing to merge from #{@merge_request.source_branch} into #{@merge_request.target_branch}
+  .nothing-here-block
+    = image_tag 'illustrations/merge_request_changes_empty.svg'
+    %p
+      Nothing to merge from
+      %strong= @merge_request.source_branch
+      into
+      %strong= @merge_request.target_branch
+
+      %p= link_to 'Create commit', project_new_blob_path(@project, @merge_request.source_branch), class: 'btn btn-save'

changelogs/unreleased/update_mr_changes_empty_page.yml

+---
+title: Update empty state page of merge request 'changes' tab
+merge_request: 15611
+author: Vitaliy @blackst0ne Klachkov
+type: added