runtime(doc): update and remove  some invalid links

closes: #14748

Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/usr_01.txt b/runtime/doc/usr_01.txt
index fafb242..fdf1b53 100644
--- a/runtime/doc/usr_01.txt
+++ b/runtime/doc/usr_01.txt
@@ -1,4 +1,4 @@
-*usr_01.txt*	For Vim version 9.1.  Last change: 2023 May 12
+*usr_01.txt*	For Vim version 9.1.  Last change: 2024 May 11
 
 		     VIM USER MANUAL - by Bram Moolenaar
 
@@ -165,7 +165,7 @@
 Moolenaar.  This material may be distributed only subject to the terms and
 conditions set forth in the Open Publication License, v1.0 or later.  The
 latest version is presently available at:
-	     http://www.opencontent.org/openpub/
+	     https://opencontent.org/openpub/
 
 People who contribute to the manuals must agree with the above copyright
 notice.