Bug in LLM Agents: Page need re-work

**Describe the bug**

Page: https://google.github.io/adk-docs/agents/llm-agents/#code-execution

Comments:

* Page content is good
* Page content structure need formatting. Started reading https://google.github.io/adk-docs/agents/llm-agents/#defining-the-agents-identity-and-purpose but the suddenly `instruction` and `tool` becomes sub-sections and so on; I believe this page is to explain LLMAgent params & how to enable or use them.
* Code Executions has bugs - https://google.github.io/adk-docs/agents/llm-agents/#code-execution does not show how to use `BaseCodeExecutor`

**To Reproduce**

NA

**Expected behavior**

NA

**Screenshots**

NA

**Versions**

- OS: [e.g. Windows, Mac, Linux]
- ADK version:
- Python version:

**Additional context**

Add any other context about the problem here.