patch 9.1.1426: completion: register contents not completed

Problem:  CTRL-X CTRL-R only completes individual words from registers,
          making it difficult to insert complete register content.
Solution: Add consecutive CTRL-X CTRL-R support - first press completes
          words, second press completes full register lines, similar to
          CTRL-X CTRL-L and CTRL-X CTRL-P behavior (glepnir).

closes: #17395

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/index.txt b/runtime/doc/index.txt
index d03d81e..ff27994 100644
--- a/runtime/doc/index.txt
+++ b/runtime/doc/index.txt
@@ -1,4 +1,4 @@
-*index.txt*     For Vim version 9.1.  Last change: 2025 May 26
+*index.txt*     For Vim version 9.1.  Last change: 2025 Jun 02
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -163,7 +163,7 @@
 |i_CTRL-X_CTRL-N|	CTRL-X CTRL-N	next completion
 |i_CTRL-X_CTRL-O|	CTRL-X CTRL-O	omni completion
 |i_CTRL-X_CTRL-P|	CTRL-X CTRL-P	previous completion
-|i_CTRL-X_CTRL-R|	CTRL-X CTRL-R	complete words from registers
+|i_CTRL-X_CTRL-R|	CTRL-X CTRL-R	complete contents from registers
 |i_CTRL-X_CTRL-S|	CTRL-X CTRL-S	spelling suggestions
 |i_CTRL-X_CTRL-T|	CTRL-X CTRL-T	complete identifiers from thesaurus
 |i_CTRL-X_CTRL-Y|	CTRL-X CTRL-Y	scroll down
diff --git a/runtime/doc/insert.txt b/runtime/doc/insert.txt
index 553183d..9ec4682 100644
--- a/runtime/doc/insert.txt
+++ b/runtime/doc/insert.txt
@@ -1,4 +1,4 @@
-*insert.txt*    For Vim version 9.1.  Last change: 2025 May 26
+*insert.txt*    For Vim version 9.1.  Last change: 2025 Jun 02
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -649,7 +649,7 @@
 11. omni completion					|i_CTRL-X_CTRL-O|
 12. Spelling suggestions				|i_CTRL-X_s|
 13. keywords in 'complete'				|i_CTRL-N| |i_CTRL-P|
-14. words from registers				|i_CTRL-X_CTRL-R|
+14. contents from registers				|i_CTRL-X_CTRL-R|
 
 Additionally, |i_CTRL-X_CTRL-Z| stops completion without changing the text.
 
@@ -1021,7 +1021,7 @@
 				:imap <Tab> <C-X><C-V>
 
 
-Completing words from registers				*compl-register-words*
+Completing contents from registers			*compl-register-words*
 							*i_CTRL-X_CTRL-R*
 CTRL-X CTRL-R		Guess what kind of item is in front of the cursor from
 			all registers and find the first match for it.
@@ -1035,6 +1035,11 @@
 	CTRL-P		Search backwards for previous match.  This match
 			replaces the previous one.
 
+	CTRL-X CTRL-R	Further use of CTRL-X CTRL-R will copy the line
+			following the previous expansion in other contexts
+			unless a double CTRL-X is used (e.g. this switches
+			from completing register words to register contents).
+
 User defined completion					*compl-function*
 
 Completion is done by a function that can be defined by the user with the
diff --git a/runtime/doc/usr_24.txt b/runtime/doc/usr_24.txt
index 250bd17..0f72495 100644
--- a/runtime/doc/usr_24.txt
+++ b/runtime/doc/usr_24.txt
@@ -1,4 +1,4 @@
-*usr_24.txt*	For Vim version 9.1.  Last change: 2018 Mar 18
+*usr_24.txt*	For Vim version 9.1.  Last change: 2025 Jun 02
 
 		     VIM USER MANUAL - by Bram Moolenaar
 
@@ -187,7 +187,7 @@
 	CTRL-X CTRL-D		macro definitions (also in included files)
 	CTRL-X CTRL-I		current and included files
 	CTRL-X CTRL-K		words from a dictionary
-	CTRL-X CTRL-R		words from registers
+	CTRL-X CTRL-R		contents from registers
 	CTRL-X CTRL-T		words from a thesaurus
 	CTRL-X CTRL-]		tags
 	CTRL-X CTRL-V		Vim command line
diff --git a/runtime/doc/vi_diff.txt b/runtime/doc/vi_diff.txt
index ae14968..b35fe77 100644
--- a/runtime/doc/vi_diff.txt
+++ b/runtime/doc/vi_diff.txt
@@ -1,4 +1,4 @@
-*vi_diff.txt*   For Vim version 9.1.  Last change: 2025 Mar 28
+*vi_diff.txt*   For Vim version 9.1.  Last change: 2025 Jun 02
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -338,7 +338,7 @@
 	|i_CTRL-X_CTRL-D|	definitions or macros
 	|i_CTRL-X_CTRL-O|	Omni completion: clever completion
 				specifically for a file type
-	|i_CTRL-X_CTRL-R|	words from registers
+	|i_CTRL-X_CTRL-R|	contents from registers
 	etc.
 
 Long line support.					|'wrap'| |'linebreak'|