Fix doc link to code suggestions in MR diff tab

Changelog: fixed

app/helpers/merge_requests_helper.rb

@@ -185,7 +185,7 @@ module MergeRequestsHelper
       endpoint_metadata: @endpoint_metadata_url,
       endpoint_batch: diffs_batch_project_json_merge_request_path(project, merge_request, 'json', params),
       endpoint_coverage: @coverage_path,
-      help_page_path: help_page_path('user/discussions/index.md', anchor: 'suggest-changes'),
+      help_page_path: help_page_path('user/project/merge_requests/reviews/suggestions.md'),
       current_user_data: @current_user_data,
       update_current_user_path: @update_current_user_path,
       project_path: project_path(merge_request.project),