Migrate "Functionality" Usage Examples into User Guide

[philipc2]

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Proposed new feature or change:

Migrate usage examples that walk through functionality without a specific use-case / workflow into a "User Guide"

Usage Examples should show UXarray in action for certain analysis or other workflow operations.

[philipc2]

Initial efforts were made in #472 , however the remaining usage examples (such as face areas) need to be migrated.