[Improvement][official website] pstree should be listed in the documentation as an application that must be installed

[Squidyu]

*For better global communication, please give priority to using English description, thx! *

Please review https://dolphinscheduler.apache.org/en-us/community/development/issue.html when describe an issue.

Describe the question
If pstree does not exist on the DS installation machine, the kill operation to stop the process will fail, and the task will continue to run

--pstree 在ds安装机器不存在的话会导致停止进程的kill操作执行失败，任务会继续运行

What are the current deficiencies and the benefits of improvement
The mandatory software on the official website indicates the need for pstree, which can avoid many users stepping on the pit
--在官网的必装软件中提示需要pstree能够避免很多用户踩坑

Which version of DolphinScheduler:
-[all]

Describe alternatives you've considered
Specify the need for pstree in the mandatory software on the official website
--在官网的必装软件中写明需要pstree

[github-actions]

*For better global communication, please give priority to using English description, thx! *

Please review https://dolphinscheduler.apache.org/en-us/community/development/issue.html when describe an issue.

Describe the question
If pstree does not exist on the DS installation machine, the kill operation to stop the process will fail, and the task will continue to run

--pstree If the ds installation machine does not exist, it will cause the kill operation to stop the process to fail, and the task will continue to run

What are the current deficiencies and the benefits of improvement
The mandatory software on the official website indicates the need for pstree, which can avoid many users stepping on the pit
--In the mandatory software on the official website, it is prompted that pstree is required to prevent many users from stepping on pits

Which version of DolphinScheduler:
-[all]

Describe alternatives you've considered
Specify the need for pstree in the mandatory software on the official website
--In the required software on the official website, specify that pstree is required

[github-actions]

Hi:

• Thank you for your feedback, we have received your issue, Please wait patiently for a reply.
• In order for us to understand your request as soon as possible, please provide detailed information、version or pictures.
• If you haven't received a reply for a long time, you can subscribe to the developer's email，Mail subscription steps reference https://dolphinscheduler.apache.org/zh-cn/community/development/subscribe.html ,Then write the issue URL in the email content and send question to dev@dolphinscheduler.apache.org.

[Squidyu]

I will bring a PR to the official website document

[Squidyu]

I will bring a PR to the official website document

I've already mentioned a pr

[davidzollo]

good job