patch 9.1.1408: not easily possible to complete from register content

Problem:  not easily possible to complete from register content
Solution: add register-completion submode using i_CTRL-X_CTRL-R
          (glepnir)

closes: #17354

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index e74c5e8..f0a7e9e 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -1,4 +1,4 @@
-*options.txt*	For Vim version 9.1.  Last change: 2025 May 16
+*options.txt*	For Vim version 9.1.  Last change: 2025 May 26
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -4658,7 +4658,8 @@
 'ignorecase' 'ic'	boolean	(default off)
 			global
 	Ignore case in search patterns, |cmdline-completion|, when
-	searching in the tags file, and non-|Vim9| |expr-==|.
+	searching in the tags file, non-|Vim9| |expr-==| and for Insert-mode
+	completion |ins-completion|.
 	Also see 'smartcase' and 'tagcase'.
 	Can be overruled by using "\c" or "\C" in the pattern, see
 	|/ignorecase|.