Verify canary release

• I verified that the issue exists in the latest Turborepo canary release.

Link to code that reproduces this issue

n/a

Which canary version will you have in your reproduction?

n/a

Environment information

n/a

Expected behavior

When using environment variables in projects, turbo expects them to be configured in turbo.json, otherwise a warning will be displayed during build process.

When building a project on vercel with missing turbo.json configuration for environment variables, the following warning is displayed:

Warning - the following environment variables are set on your Vercel project, but missing from "turbo.json". These variables WILL NOT be available to your application and may cause your build to fail. Learn more at https://turborepo.com/docs/platform-environment-variables

I expect the link to point to a docs page that explains how to use platform environment variables.

Actual behavior

The current link in the warning is invalid and leads to a 404 "lost in the Turboverse..." page.

To Reproduce

1. Add am environment variable to your project
2. Do not set it up in turbo.json
3. Deploy to Vercel
4. Look at the deployment logs
5. Try to navigate to the previously mentioned link you should see in your logs

Additional context

The correct link is https://turborepo.com/docs/crafting-your-repository/using-environment-variables#platform-environment-variables

and the line that is actually providing the incorrect link is here @ platform.rs#L67

I'm happy to correct this with a PR :)