Docs: update installation section

[yangchuansheng]

🤖 Generated by Copilot at 0d67a75

Summary

🐛📝🌐

This pull request updates and fixes some documentation files for the Chinese version of sealos. It improves the self-hosting installation guide, corrects some typos and JSON errors in the navbar and footer files, and makes the website more user-friendly and consistent.

Some changes were made to the site
To make it more accurate and bright
The footer.json had a typo
The installation.md got some info
And the navbar.json was fixed right

Walkthrough

• Add frontmatter attribute to specify maximum heading level for table of contents in installation.md document (link)
• Update server requirements section in installation.md document with basic requirements, recommended configuration, and operating system support (link)
• Modify certificate section in installation.md document with blank line, punctuation, and more details (link, link)
• Fix typos and remove trailing comma in footer.json and navbar.json files (link, link, link)

[sealos-ci-robot]

🤖 Generated by lychee action

Summary

Status	Count
🔍 Total	980
✅ Successful	378
⏳ Timeouts	0
🔀 Redirected	0
👻 Excluded	601
❓ Unknown	0
🚫 Errors	0

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• Apply: Leftover TODOs in the code should be handled.
• Apply: All new business logic should have corresponding unit tests in the tests/ directory.
• Apply: Any clearly inefficient or repeated code should be optimized or refactored.

[sealos-ci-robot]

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