[TRANSLATION] Update vietnamese version for unit 2 + 3

[honghanhh]

@ngxson please feel free to review it.
After your review and approval, @burtenshaw please check for final approval.

Thanks.

[sergiopaniego]

Thanks a lot for the update! 🤗
In order to merge it, we need to update the agents-course/units/vi/_toctree.yml. accordingly pointing to the new sections.

For reference, these are the sections missing:

RuntimeError: The following files are not present in the table of contents:
- unit2/introduction
- unit2/llama-index/quiz1
- unit2/llama-index/agents
- unit2/llama-index/introduction
- unit2/llama-index/tools
- unit2/llama-index/components
- unit2/llama-index/llama-hub
- unit2/llama-index/workflows
- unit2/llama-index/quiz2
- unit2/llama-index/conclusion
- unit2/langgraph/quiz1
- unit2/langgraph/document_analysis_agent
- unit2/langgraph/when_to_use_langgraph
- unit2/langgraph/building_blocks
- unit2/langgraph/introduction
- unit2/langgraph/first_graph
- unit2/langgraph/conclusion
- unit2/smolagents/quiz1
- unit2/smolagents/tool_calling_agents
- unit2/smolagents/introduction
- unit2/smolagents/tools
- unit2/smolagents/multi_agent_systems
- unit2/smolagents/vision_agents
- unit2/smolagents/code_agents
- unit2/smolagents/why_use_smolagents
- unit2/smolagents/quiz2
- unit2/smolagents/retrieval_agents
- unit2/smolagents/conclusion
- unit2/smolagents/final_quiz
Add them to ../agents-course/units/vi/_toctree.yml.

Would you mind updating it?
Thanks again!

[ngxson]

Thanks @honghanhh , and sorry for the long delay. This seems good overall, I'll do a proper review later this week.

In the meantime, would be nice if you can fix the problem with _toctree. Feel free to tell me if you need help with that!

[wantingchen0852]

I think this translation update looks very helpful. I noticed the "_toctree.yml" issue mentioned above, once that's fixed, this seems like a solid addition.

[ngxson]

Sorry for the long delay, I'll try to merge it this week. Thanks a lot for the contribution 🔥

[sergiopaniego]

Thanks for the update!

The build process is still struggling to generate the page. In particular, it's generating the following exception:

96 |  <p>Cách tiếp cận này kết hợp tri thức định sẵn với tìm kiếm ngữ nghĩa để đưa ra giải pháp theo ngữ cảnh cho việc lập kế hoạch sự kiện. Với quyền truy cập vào tri thức chuyên sâu, Alfred có thể hoàn thiện từng chi tiết của bữa tiệc.</p>
  97 |  <p>Trong ví dụ này, chúng ta sẽ tạo công cụ truy xuất ý tưởng lập kế hoạch tiệc từ cơ sở tri thức tùy chỉnh. Sử dụng BM25 retriever để tìm kiếm và <code>RecursiveCharacterTextSplitter</code> để chia tài liệu thành các đoạn nhỏ.</p>
  98 |  <details>
        ^
  99 |  <summary>Bấm để xem bản dịch tiếng Việt</summary>
 100 |  ```python
error during build:
ParseError: <details> was left open
    at error (file:///tmp/tmps8dzms8f/kit/node_modules/svelte/src/compiler/utils/error.js:56:16)
    at Parser.error (file:///tmp/tmps8dzms8f/kit/node_modules/svelte/src/compiler/parse/index.js:143:3)
    at new Parser (file:///tmp/tmps8dzms8f/kit/node_modules/svelte/src/compiler/parse/index.js:97:9)
    at parse (file:///tmp/tmps8dzms8f/kit/node_modules/svelte/src/compiler/parse/index.js:268:17)
    at Module.compile (file:///tmp/tmps8dzms8f/kit/node_modules/svelte/src/compiler/compile/index.js:136:14)
    at compileSvelte (file:///tmp/tmps8dzms8f/kit/node_modules/@sveltejs/vite-plugin-svelte/src/utils/compile.js:128:27)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async Object.transform (file:///tmp/tmps8dzms8f/kit/node_modules/@sveltejs/vite-plugin-svelte/src/index.js:223:20)
    at async transform (file:///tmp/tmps8dzms8f/kit/node_modules/rollup/dist/es/shared/node-entry.js:24367:16)
    at async ModuleLoader.addModuleSource (file:///tmp/tmps8dzms8f/kit/node_modules/rollup/dist/es/shared/node-entry.js:24567:30)
Traceback (most recent call last):
Installing node dependencies
  File "/home/runner/work/agents-course/agents-course/.venv/bin/doc-builder", line 10, in <module>
    sys.exit(main())
  File "/home/runner/work/agents-course/agents-course/.venv/lib/python3.10/site-packages/doc_builder/commands/doc_builder_cli.py", line 47, in main
    args.func(args)
  File "/home/runner/work/agents-course/agents-course/.venv/lib/python3.10/site-packages/doc_builder/commands/build.py", line 170, in build_command
    subprocess.run(
  File "/usr/lib/python3.10/subprocess.py", line 526, in run
Building HTML files. This will take a while :-)
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['npm', 'run', 'build']' returned non-zero exit status 1.

It seems like there are some special tag that weren't part of the original text (<details> and <summary>). Could we review it, removing any additional tag? Thanks!