Add a text in docs to prevent using -- for comment.

[woraperth]

The error message (local variable 'connection' referenced before assignment) when using -- doesn't indicate the actual syntax error. It is also not documented

What are you changing in this pull request and why?

Stumbled upon error from this issue and tried to debug it for few hours until I realised this error. Adding text in the docs to prevent other developers finding the same issue.

Checklist

• I have reviewed the Content style guide so my content adheres to these guidelines.
• The topic I'm writing about is for specific dbt version(s) and I have versioned it according to the version a whole page and/or version a block of content guidelines.
• I have added checklist item(s) to this list for anything anything that needs to happen before this PR is merged, such as "needs technical review" or "change base branch."

[welcome]

Hello!👋 Thanks for contributing to the dbt product documentation and opening this pull request! ✨
We use Markdown and some HTML to write the dbt product documentation. When writing content, you can use our style guide and content types to understand our writing standards and how we organize information in the dbt product docs.
We'll review your contribution and respond as soon as we can. 😄

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[mirnawong1]

hey @woraperth , great callout and thank you so much for adding this to the docs and looking out for other developers! looks great and merging for you!

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Name	Status	Preview	Updated (UTC)
docs-getdbt-com	✅ Ready (Inspect)	Visit Preview	Sep 5, 2024 9:07am