Modify Helptext while keeping help for verbs

Hi,

I tried to follow the wiki at https://github.com/commandlineparser/commandline/wiki/HelpText-Configuration, and while it seems this works for --help, it does not work for --help.

For the verb it all works as expected, but in the second case, suddenly the help doesn't mention which verbs are available. I tried both mapresult, withparsed/notparsed. But the behaviour stayed the same in all occasions.

先使用 HelpText Configuration wiki 重現 issue 中描述的兩種命令形式： --help 和 --help。追蹤已設定的說明文字在每種情況下如何套用。當自訂說明仍可使用，且頂層說明也列出可用的 verb 時，即表示完成。

由索引模型根據 Issue 內容生成。