patch 8.2.4050: Vim9: need to prefix every item in an autoload script

Problem:    Vim9: need to prefix every item in an autoload script.
Solution:   First step in supporting "vim9script autoload" and "import
            autoload".
diff --git a/runtime/doc/repeat.txt b/runtime/doc/repeat.txt
index 25f375e..407c23c 100644
--- a/runtime/doc/repeat.txt
+++ b/runtime/doc/repeat.txt
@@ -365,11 +365,12 @@
 			Vim version, or update Vim to a newer version.  See
 			|vimscript-version| for what changed between versions.
 
-:vim9s[cript] [noclear]				*:vim9s* *:vim9script*
+:vim9s[cript] [noclear] [autoload]			*:vim9s* *:vim9script*
 			Marks a script file as containing |Vim9-script|
 			commands.  Also see |vim9-namespace|.
 			Must be the first command in the file.
 			For [noclear] see |vim9-reload|.
+			For [autoload] see |vim9-autoload|.
 			Without the |+eval| feature this changes the syntax
 			for some commands.
 			See |:vim9cmd| for executing one command with Vim9