Instructions for viewing the dev docs locally are wrong

[navidcy]

I believe that after #5159 the instructions for how to view the documentation locally are not working. In particular, building the documentation works OK, but then the line that explains how to view it in your local browser

Oceananigans.jl/docs/src/developer_docs/contributing.md

Line 181 in f4a26d1

If the documentation built is successful, you can open `docs/build/index.html` in your favorite browser.Providing the environment variable

is inaccurate. I couldn't figure out how to view the docs locally. @lazarusA, any insights?

[lazarusA]

https://luxdl.github.io/DocumenterVitepress.jl/stable/manual/get_started#Live-Development-Workflow