runtime(doc): Update doc 52.6

Problem: the highlight-yank plugin exmaple provided in the doc behaves
	 incorrectly when selection is set to exclusive.

Solution: use a unified offset of 1 and pass 'exclusive: false' to
	  getregionpos(), while at it, also clarify when the
          TextYankPost autocommand triggers.

closes: #16866

Signed-off-by: Jim Zhou <jimzhouzzy@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/autocmd.txt b/runtime/doc/autocmd.txt
index 5c44958..8532fc9 100644
--- a/runtime/doc/autocmd.txt
+++ b/runtime/doc/autocmd.txt
@@ -1,4 +1,4 @@
-*autocmd.txt*   For Vim version 9.1.  Last change: 2025 Mar 08
+*autocmd.txt*   For Vim version 9.1.  Last change: 2025 Mar 12
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1346,6 +1346,10 @@
 				called recursively.
 				It is not allowed to change the buffer text,
 				see |textlock|. *E1064*
+				Also triggered indirectly when Vim tries to
+				become owner of the Visual selection because
+				of setting "autoselect" for 'guioptions' or
+				'clipboard'.
 				{only when compiled with the +eval feature}
 
 							*User*
diff --git a/runtime/doc/usr_52.txt b/runtime/doc/usr_52.txt
index dbfd319..6a8204d 100644
--- a/runtime/doc/usr_52.txt
+++ b/runtime/doc/usr_52.txt
@@ -1,4 +1,4 @@
-*usr_52.txt*	For Vim version 9.1.  Last change: 2024 Oct 07
+*usr_52.txt*	For Vim version 9.1.  Last change: 2025 Mar 12
 
 		     VIM USER MANUAL - by Bram Moolenaar
 
@@ -362,11 +362,10 @@
 	    endif
 	    var [beg, end] = [getpos("'["), getpos("']")]
 	    var type = v:event.regtype ?? 'v'
-	    var pos = getregionpos(beg, end, {type: type})
-	    var end_offset = (type == 'V' || v:event.inclusive) ? 1 : 0
+	    var pos = getregionpos(beg, end, {type: type, exclusive: false})
 	    var m = matchaddpos(hlgroup, pos->mapnew((_, v) => {
 	      var col_beg = v[0][2] + v[0][3]
-	      var col_end = v[1][2] + v[1][3] + end_offset
+	      var col_end = v[1][2] + v[1][3] + 1
 	      return [v[0][1], col_beg, col_end - col_beg]
 	    }))
 	    var winid = win_getid()