docs: delete stream.md && supplement stream description to client

[chaoranz758]

What type of PR is this?

docs

Check the PR title.

• This PR title match the format: <type>(optional scope): <description>
• The description of this PR title is user-oriented and clear enough for others to understand.

(Optional) Translate the PR title into Chinese.

删除独立的流式处理文件，并在client和engine中补充说明流式处理的内容

(Optional) More detailed description for this PR(en: English/zh: Chinese).

en:docs: delete stream.md && supplement stream description to client
zh(optional): docs: 删除独立的流式处理文件，并在client和engine中补充说明流式处理的内容

(Optional) Which issue(s) this PR fixes:

Fixes #606

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Name	Status	Preview	Comments	Updated (UTC)
cloudwego	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Aug 20, 2023 5:28am

[li-jin-gou]

@chaoranz758 确定一下流式的文档，还有别的地方引用嘛

[rogerogers]

cloudwego.github.io/content/zh/blog/releases/Hertz/release-v050.md

Line 36 in d96c179

更多详细的设计说明可以参考：[Hertz 支持 QUIC & HTTP/3](https://www.cloudwego.io/zh/docs/hertz/reference/stream_based_design/)

这个链接不存在，这个stream是这里吗

[li-jin-gou]

cloudwego.github.io/content/zh/blog/releases/Hertz/release-v050.md

Line 36 in d96c179

更多详细的设计说明可以参考：[Hertz 支持 QUIC & HTTP/3](https://www.cloudwego.io/zh/docs/hertz/reference/stream_based_design/)

这个链接不存在，这个stream是这里吗

这个 pr 引入的问题 4d259fc cc @chaoranz758