docs: review essentials part of zh translation

[KiritaniAyaka]

What this PR does:

• Improved some translations.
• Fixed some problems that make markdown render incorrectly.
• Synced new contents from the English version.
• Translated comments in the code snippets.
• Added translation for hooks.md.
• The current translation has both "keep original" and "translate to Chinese" for some words. Uniformly translated to Chinese. (Signal to 信号、Context to 上下文、Hook to 钩子)