patch 8.2.3941: SIGTSTP is not handled

Problem:    SIGTSTP is not handled.
Solution:   Handle SIGTSTP like pressing CTRL-Z. (closes #9422)
diff --git a/runtime/doc/autocmd.txt b/runtime/doc/autocmd.txt
index e620f5c..c1aee0e 100644
--- a/runtime/doc/autocmd.txt
+++ b/runtime/doc/autocmd.txt
@@ -1279,8 +1279,8 @@
 	:autocmd VimResume * checktime
 <							*VimSuspend*
 VimSuspend			When the Vim instance is suspended.  Only when
-				CTRL-Z was typed inside Vim, not when the
-				SIGSTOP or SIGTSTP signal was sent to Vim.
+				CTRL-Z was typed inside Vim, or when the SIGTSTP
+				signal was sent to Vim, but not for SIGSTOP.
 							*WinClosed*
 WinClosed			After closing a window.  The pattern is
 				matched against the |window-ID|.  Both