Update link to documentation

app/views/projects/merge_requests/show/_how_to_merge.html.haml

@@ -49,7 +49,7 @@
           %strong Tip:
           = succeed '.' do
             You can also checkout merge requests locally by
-            = link_to 'following these guidelines', help_page_path('user/project/merge_requests.md', anchor: "checkout-merge-requests-locally"), target: '_blank', rel: 'noopener noreferrer'
+            = link_to 'following these guidelines', help_page_path('user/project/merge_requests/index.md', anchor: "checkout-merge-requests-locally"), target: '_blank', rel: 'noopener noreferrer'
 
 :javascript
   $(function(){