[BD-3275] Unity cleanup

[internetisaiah]

Why are you making this change? (required)

Cleaning up the Unity docs as a part of the developer detangle project.

Related PRs, issues, or features (optional)

• BD-3275

Feature release date (optional)

• N/A

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[internetisaiah]

Changes look good, just need to set up redirects.

[rachel-feinberg]

Lgtm!