runtime(help): Unset 'comments' and 'cms' options

Problem:  Vim's help file doesn't have any syntax for comments, but
          'comments' and 'commentstring' are still set in the help
          buffer.
Solution: Unset 'comments' and 'cms' in help buffer

closes: #17889

Signed-off-by: Phạm Bình An <111893501+brianhuster@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: brianhuster

runtime/ftplugin/help.vim

@@ -3,6 +3,7 @@
 " Previous Maintainer:  Nikolai Weibull <now@bitwi.se>
 " Last Change:          2025 Apr 08
 " 2025 Apr 08 by Vim project (set 'omnifunc' and 'iskeyword', #17073)
+" 2025 Aug 08 by Vim project (unset comment options, #17889)
 
 if exists("b:did_ftplugin")
   finish
@@ -12,7 +13,9 @@ let b:did_ftplugin = 1
 let s:cpo_save = &cpo
 set cpo&vim
 
-let b:undo_ftplugin = "setl isk< fo< tw< cole< cocu< keywordprg< omnifunc<"
+let b:undo_ftplugin = "setl isk< fo< tw< cole< cocu< keywordprg< omnifunc< comments< cms<"
+
+setl comments= cms=
 
 setlocal formatoptions+=tcroql textwidth=78 keywordprg=:help omnifunc=s:HelpComplete
 let &l:iskeyword='!-~,^*,^|,^",192-255'