Ensure all available environment variables are documented

[steviecoaster]

What New Or Updated Would You Like To See?

The environment variable user_context is missing from the list of available variables within a package. We should update this, while also doing a once-over for any others that are missing and document those as well.

Why Is It Needed?

It is reasonable that all available env variables that can be used have documentation about what they are and what they do.

Additional Context?

[pauby]

Please hold off on documenting this just yet. I want to follow up with the team internally first.

[pauby]

As an update to this, we want to look at all the environment variables and make sure there is consistent naming. Once this is done, Engineering will update the documentation under this issue.