Update runtime files.
diff --git a/runtime/doc/fold.txt b/runtime/doc/fold.txt
index 5bcadda..cda3902 100644
--- a/runtime/doc/fold.txt
+++ b/runtime/doc/fold.txt
@@ -507,7 +507,7 @@
     :function MyFoldText()
     :  let line = getline(v:foldstart)
     :  let sub = substitute(line, '/\*\|\*/\|{{{\d\=', '', 'g')
-    :  return v:folddashes . sub
+    :  return v:folddashes .. sub
     :endfunction
 
 Evaluating 'foldtext' is done in the |sandbox|.  The current window is set to