docs: fix broken link and improve readability

[fyvri]

This PR includes several minor but important updates to improve readability, consistency, and correctness across the documentation. Below is a summary of the changes:

1. HTML Entity Fix:
   Replaced &nbsp&nbsp with    to ensure proper usage of HTML entities.
2. Spacing Around Pipes in Links:
   Added spaces around pipes (|) in link groupings for better readability. For example: EN|ZH → EN | ZH.
3. Word Choice Improvements:
   • Replaced "Temporarily" with "Currently" where appropriate to better reflect ongoing states or conditions.
   • Clarified instances of "advise" by replacing them with "recommend," which is more precise in context.
4. Citation Formatting:
   Added ```BibTeX to citation blocks for consistency and easier identification of BibTeX content.
5. Broken Link Fix:
   Updated a broken link from assets/wechat.png to its full path: https://github.com/QwenLM/Qwen/blob/main/assets/wechat.png.

These changes collectively enhance the clarity, accuracy, and maintainability of the documentation. Let me know if there are any additional suggestions! 🙌