docs: corrent weixin_oc wechat version requirements

[tlw00988]

Modifications / 改动点

经过实践检测，在Android微信8.0.69下，也有ClawBot插件可用，而无需更新到微信8.0.70(事实上Android也没有这个版本号）

• This is NOT a breaking change. / 这不是一个破坏性变更。

Screenshots or Test Results / 运行截图或测试结果

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Checklist / 检查清单

• 😊 If there are new features added in the PR, I have discussed it with the authors through issues/emails, etc.
  / 如果 PR 中有新加入的功能，已经通过 Issue / 邮件等方式和作者讨论过。
  （我压根没加功能哈哈）

• 👀 My changes have been well-tested, and "Verification Steps" and "Screenshots" have been provided above.
  / 我的更改经过了良好的测试，并已在上方提供了“验证步骤”和“运行截图”。

• 🤓 I have ensured that no new dependencies are introduced, OR if new dependencies are introduced, they have been added to the appropriate locations in requirements.txt and pyproject.toml.
  / 我确保没有引入新依赖库，或者引入了新依赖库的同时将其添加到 requirements.txt 和 pyproject.toml 文件相应位置。

• 😮 My changes do not introduce malicious code.
  / 我的更改没有引入恶意代码。

Summary by Sourcery

Documentation:

• Clarify Weixin OC adapter documentation with separate minimum WeChat versions for iOS (>= 8.0.70) and Android (>= 8.0.69) and note the need for the ClawBot plugin.

[sourcery-ai]

Hey - I've left some high level feedback:

• The updated requirement string mixes iOS and Android in a single sentence; consider splitting into two bullet points or lines (one for iOS, one for Android) to improve readability and avoid confusion.
• The phrase 确保插件内有插件微信ClawBot is a bit ambiguous; you might clarify whether users should verify the ClawBot plugin is installed, enabled, or visible in a specific location in the UI.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The updated requirement string mixes iOS and Android in a single sentence; consider splitting into two bullet points or lines (one for iOS, one for Android) to improve readability and avoid confusion.
- The phrase `确保插件内有插件微信ClawBot` is a bit ambiguous; you might clarify whether users should verify the ClawBot plugin is installed, enabled, or visible in a specific location in the UI.

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[gemini-code-assist]

Code Review

This pull request updates the WeChat adapter documentation to specify minimum version requirements for iOS (8.0.70) and Android (8.0.69) and adds a note regarding the ClawBot plugin. Feedback was provided to improve the phrasing and formatting of this note for better clarity and consistency.