Clean up and update docs folder

[zhihali]

We need to perform a comprehensive cleanup and update of the docs folder in our OpenTelemetry Python repository. This task was discussed in our recent SIG meeting(JUL 25), and it's crucial for maintaining the quality and relevance of our documentation.

Current situation:

• Some documents in the docs folder are outdated
• There's a mix of documents used in new documentation and legacy content
• Some Python doc files are present and tested but not published(and looks will not publish anymore)
• Potential inconsistencies between our repo docs and opentelemetry.io documentation

Proposed actions:

1. Thoroughly review all documents in the docs folder
2. Compare our repo docs with the opentelemetry.io documentation
3. Identify and retain valuable, up-to-date content
4. Remove outdated or unused documents
5. Ensure all published Python doc files are relevant and current

Next steps:

1. Categorize documents as:
   • Up-to-date and in use
   • Needs updating
   • Obsolete and can be removed
   • Unpublished but potentially useful
2. Discuss findings in upcoming SIG meetings
3. Create follow-up issues for specific cleanup tasks or updates

This cleanup will improve the maintainability of our documentation and ensure that users have access to current, relevant information.

Note: This may require multiple steps and discussions. Follow-up issues will be created as needed to address specific aspects of this cleanup process.

And I would love to implement these.🤓

/cc @emdneto @lzchen