patch 9.1.1202: Missing TabClosedPre autocommand

Problem:  Missing TabClosedPre autocommand
          (zoumi)
Solution: Add the TabClosedPre autcommand (Jim Zhou).

fixes: #16518
closes: #16855

Signed-off-by: Jim Zhou <jimzhouzzy@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/autocmd.txt b/runtime/doc/autocmd.txt
index 8532fc9..372d1ac 100644
--- a/runtime/doc/autocmd.txt
+++ b/runtime/doc/autocmd.txt
@@ -387,6 +387,7 @@
 |TabNew|		after creating a new tab page
 |WinClosed|		after closing a window
 |TabClosed|		after closing a tab page
+|TabClosedPre|		before closing a tab page
 |WinEnter|		after entering another window
 |WinLeave|		before leaving a window
 |TabEnter|		after entering another tab page
@@ -1232,6 +1233,10 @@
 				See |:syn-on|.
 							*TabClosed*
 TabClosed			After closing a tab page.
+							*TabClosedPre*
+TabClosedPre			Before closing a tab page.  The window layout
+				is locked, thus opening and closing of windows
+				is prohibited.
 							*TabEnter*
 TabEnter			Just after entering a tab page. |tab-page|
 				After triggering the WinEnter and before