runtime(doc): add reference to extendnew() at extend()
related: #16607
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index e2d2f43..344dfdf 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -1,4 +1,4 @@
-*builtin.txt* For Vim version 9.1. Last change: 2025 Feb 06
+*builtin.txt* For Vim version 9.1. Last change: 2025 Feb 17
VIM REFERENCE MANUAL by Bram Moolenaar
@@ -3006,7 +3006,8 @@
When {expr3} is omitted then "force" is assumed.
{expr1} is changed when {expr2} is not empty. If necessary
- make a copy of {expr1} first.
+ make a copy of {expr1} first or use |extendnew()| to return a
+ new List/Dictionary.
{expr2} remains unchanged.
When {expr1} is locked and {expr2} is not empty the operation
fails.