runtime(doc): remove obsolete Ex insert behavior

related: #15120
closes: #15228

Signed-off-by: Mohamed Akram <mohd.akram@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/insert.txt b/runtime/doc/insert.txt
index 6ebd83e..08bf4f3 100644
--- a/runtime/doc/insert.txt
+++ b/runtime/doc/insert.txt
@@ -1,4 +1,4 @@
-*insert.txt*    For Vim version 9.1.  Last change: 2024 Jan 04
+*insert.txt*    For Vim version 9.1.  Last change: 2024 Jul 12
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1995,11 +1995,6 @@
 containing only a ".".  Watch out for lines starting with a backslash, see
 |line-continuation|.
 
-When in Ex mode (see |-e|) a backslash at the end of the line can be used to
-insert a NUL character.  To be able to have a line ending in a backslash use
-two backslashes.  This means that the number of backslashes is halved, but
-only at the end of the line.
-
 NOTE: These commands cannot be used with |:global| or |:vglobal|.
 ":append" and ":insert" don't work properly in between ":if" and
 ":endif", ":for" and ":endfor", ":while" and ":endwhile".