Update runtime files.
diff --git a/runtime/doc/windows.txt b/runtime/doc/windows.txt
index 90a1789..0b96115 100644
--- a/runtime/doc/windows.txt
+++ b/runtime/doc/windows.txt
@@ -1,4 +1,4 @@
-*windows.txt* For Vim version 8.1. Last change: 2018 Apr 24
+*windows.txt* For Vim version 8.1. Last change: 2019 Mar 17
VIM REFERENCE MANUAL by Bram Moolenaar
@@ -842,6 +842,12 @@
{not available when the |+file_in_path| feature was disabled
at compile time}
+CTRL-W gt *CTRL-W_gt*
+ Go to next tab page, same as `gt`.
+
+CTRL-W gT *CTRL-W_gT*
+ Go to previous tab page, same as `gT`.
+
Also see |CTRL-W_CTRL-I|: open window for an included file that includes
the keyword under the cursor.