[DOC] remove audience and usage from preamble

[acocac]

Before review

• Work in progress
• Ready for review
• Need help!

Description

• Merge about and audience sections
• Update attributions and how to contribute

Motivation and Context

Facilitates the navigation in the preamble chapter.

How has this been tested?

Local. MacOs.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• New notebook and/or content
• Documentation notebook/content update
• Other (please describe):
• Feature change (upgrade version)

Checklist:

• My code follows the code style of this project: Python
• I have read the CONTRIBUTING doc
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests to cover my changes
• I have tested the changes and verified that they work and don't break anything (as well as I can manage)

Additional information

[netlify]

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