patch 8.2.0996: using "aucmdwin" in win_gettype() is not ideal

Problem:    Using "aucmdwin" in win_gettype() is not ideal.
Solution:   Rename to "autocmd".
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index fe2e94e..6da5046 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -10864,7 +10864,7 @@
 
 win_gettype([{nr}])					*win_gettype()*
 		Return the type of the window:
-			"aucmdwin"	autocommand window. Temporary window
+			"autocmd"	autocommand window. Temporary window
 					used to execute autocommands.
 			"popup"		popup window |popup|
 			"preview"	preview window |preview-window|