Update runtime files.
diff --git a/runtime/doc/windows.txt b/runtime/doc/windows.txt
index 8e8b0bb..be26841 100644
--- a/runtime/doc/windows.txt
+++ b/runtime/doc/windows.txt
@@ -1,4 +1,4 @@
-*windows.txt* For Vim version 8.0. Last change: 2017 Aug 21
+*windows.txt* For Vim version 8.0. Last change: 2017 Sep 08
VIM REFERENCE MANUAL by Bram Moolenaar
@@ -1034,6 +1034,7 @@
= a readonly buffer
R a terminal buffer with a running job
F a terminal buffer with a finished job
+ ? a terminal buffer without a job: `:terminal NONE`
+ a modified buffer
x a buffer with read errors