help.txt: Update Vim 9.0.0701

tsuyoshicho · tsuyoshicho · commit 055e1e6881d3 · 2022-10-10T14:01:38.000+09:00
diff --git a/en/help.txt b/en/help.txt
@@ -141,6 +141,7 @@ Advanced editing ~
 |autocmd.txt|	automatically executing commands on an event
 |eval.txt|	expression evaluation, conditional commands
 |builtin.txt|	builtin functions
+|userfunc.txt|	defining user functions
 |channel.txt|	Jobs, Channels, inter-process communication
 |fold.txt|	hide (fold) ranges of lines
 
