Update contribute section of the docs

[discdiver]

• Moves contribute section out of versioned docs, as the material should be version agnostic.
• Updates docs contributing section for 3.0.
• Breaks out code of conduct.

Checklist

• This pull request references any related issue by including "closes <link to issue>"
  • If no issue exists and your change is not a small fix, please create an issue first.
• If this pull request adds new functionality, it includes unit tests that cover the changes
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For documentation changes:

• This pull request includes redirect settings in mint.json for files that are removed or renamed.

For new functions or classes in the Python SDK:

• This pull request includes helpful docstrings.
• If a new Python file was added, this pull request contains a stub page in the Python SDK docs and an entry in docs/mint.json navigation.

[billpalombi]

🚀