feat: allow users to configure pypi details

[armandobelardo]

Users can now specify information that will appear in their pypi record.

generators:
  - name: fernapi/fern-python-sdk
    metadata:
      description: this is the desc for my package
      keywords:
        - science
        - data analysis
      documentation-link: "https://buildwithfern.com/learn"
      homepage-link: "https://buildwithfern.com/"
      authors:
        - email: support@buildwithfern.com
          name: Armando