Adjust package documentation

[jzhu13]

What are you changing in this pull request and why?

When the Metadata team was looking into a customer issue we noticed that their project which used a package was receiving sources from that package. After double checking the documentation it seems that packages only mention models and macros being part of package behavior, which is misleading.

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."
• The content in this PR requires a dbt release note, so I added one to the release notes page.

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🚀 Deployment available! Here are the direct links to the updated files:

• https://docs-getdbt-com-git-packagedocs-dbt-labs.vercel.app/docs/build/packages

[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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Name	Status	Preview	Updated (UTC)
docs-getdbt-com	✅ Ready (Inspect)	Visit Preview	Oct 25, 2024 9:16pm

[runleonarun]

Approved with a tech review from Joel