Update pow mining documentation

[darwintree]

Describe the feature or improvement 描述新特性或改进 Improve the mining documentation for miners.

Affected page(s) or section(s) 受影响的页面 docs/general/mine-stake/mine/running-mining-node

Why is this feature or improvement important? 为什么需要这个新特性或改进？ Explain why this feature or improvement would benefit the documentation and its users.

Optional: Implementation ideas 可选：如何实现

• reorganize the article structure
• make sure the tutorial is not outdated on any platform
• (would be better) a video showing how to mine for conflux

Optional: Additional context：可选：其他上下文信息 Add any other context, screenshots, or relevant information about the feature or improvement.

• [ ] I'd be willing to contribute this feature myself. 我将自己实现这个feature

[darwintree]

or create faq

[intrepidcanadian]

I'd like to take this on. I can show a tutorial on how to set your gpu to mining conflux