docs: add FAQ and best practice docs

[cqqqq777]

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Name	Status	Preview	Comments	Updated (UTC)
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[AsterDY]

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Name Status Preview Comments Updated (UTC) cloudwego ❌ Failed (Inspect) May 1, 2024 4:04pm

预览部署挂了？

[GuangmingLuo]

Error: Error building site: "/vercel/path0/content/en/docs/kitex/Tutorials/code-gen/custom_struct_tags.md:7:1": failed to unmarshal YAML: yaml: line 6: did not find expected comment or line break