Update runtime files.
diff --git a/runtime/doc/vi_diff.txt b/runtime/doc/vi_diff.txt
index 0fb29e4..89ef4bb 100644
--- a/runtime/doc/vi_diff.txt
+++ b/runtime/doc/vi_diff.txt
@@ -1,4 +1,4 @@
-*vi_diff.txt*   For Vim version 8.2.  Last change: 2020 Aug 15
+*vi_diff.txt*   For Vim version 8.2.  Last change: 2021 Jan 21
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar