Update runtime files

runtime/doc/usr_41.txt

@@ -1,4 +1,4 @@
-*usr_41.txt*	For Vim version 8.2.  Last change: 2020 Jun 01
+*usr_41.txt*	For Vim version 8.2.  Last change: 2020 Jun 13
 
 		     VIM USER MANUAL - by Bram Moolenaar
 
@@ -41,10 +41,11 @@ prefer.  And you can use any colon command in it (commands that start with a
 specific file type.  A complicated macro can be defined by a separate Vim
 script file.  You can think of other uses yourself.
 
-Note: if you are familiar with Python, you can find a comparison between
-Python and Vim script here, with pointers to other documents:
-   https://gist.github.com/yegappan/16d964a37ead0979b05e655aa036cad0
-
+	If you are familiar with Python, you can find a comparison between
+	Python and Vim script here, with pointers to other documents:
+	   https://gist.github.com/yegappan/16d964a37ead0979b05e655aa036cad0
+	And if you are familiar with Javascript:
+	   https://w0rp.com/blog/post/vim-script-for-the-javascripter/
 
 Let's start with a simple example: >
 
@@ -98,6 +99,8 @@ and the value of the variable i.  Since i is one, this will print:
 Then there is the ":let i += 1" command.  This does the same thing as
 ":let i = i + 1".  This adds one to the variable i and assigns the new value
 to the same variable.
+Note: this is how it works in legacy Vim script, which is what we discuss in
+this file.  In Vim9 script it's a bit different, see |usr_46.txt|.
 
 The example was given to explain the commands, but would you really want to
 make such a loop, it can be written much more compact: >