docs: refresh contributing docs

[dreamorosi]

Description of your changes

As described in the linked issue, the contribution document was missing info on how to build and package the utilities locally, a workflow that can be useful for maintainers, contributors, and customers who might want to test unreleased versions of the toolkit.

The PR adds a new dedicated section to this topic as well as revisiting some of the sections and flow of the document overall.

Related issues, RFCs

Issue number: #1525

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my change is effective and works
• The PR title follows the conventional commit semantics

Breaking change checklist

Is it a breaking change?: NO

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

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