Add missing translation (#33900)

options/locale/locale_en-US.ini

@@ -113,6 +113,7 @@ copy_type_unsupported = This file type cannot be copied
 write = Write
 preview = Preview
 loading = Loading…
+files = Files
 
 error = Error
 error404 = The page you are trying to reach either <strong>does not exist</strong> or <strong>you are not authorized</strong> to view it.

templates/repo/view_file_tree.tmpl

@@ -4,7 +4,7 @@
 		data-tooltip-content="{{ctx.Locale.Tr "repo.diff.hide_file_tree"}}">
 		{{svg "octicon-sidebar-expand"}}
 	</button>
-	<b>Files</b>
+	<b>{{ctx.Locale.Tr "files"}}</b>
 </div>
 
 {{/* TODO: Dynamically move components such as refSelector and createPR here */}}