fix(docs): Change `secrets.TURBO_TEAM` to `vars.TURBO_TEAM` (#4975)
### Description
In the [CI Docs for GitHub
Actions](https://turbo.build/repo/docs/ci/github-actions) there are
instructions to use a repository variable for the `TURBO_TEAM`.
> Using a repository variable rather than a secret will keep Github
Actions from censoring your team name in the log output.
In current documentation, the GitHub Action yml instructs using
`secrets.TURBO_TEAM`:
```yml
env:
TURBO_TOKEN: ${{ secrets.TURBO_TOKEN }}
TURBO_TEAM: ${{ secrets.TURBO_TEAM }}
```
In this case, the log output will be:
```
env:
TURBO_TOKEN: ***
TURBO_TEAM:
```
Meaning `TURBO_TEAM` has an empty string.
This PR changes `secrets.TURBO_TEAM` to `vars.TURBO_TEAM` in the docs.
This change will lead to correct behavior in the log:
```
env:
TURBO_TOKEN: ***
TURBO_TEAM: my_team_id
```
[Reference for `vars`
context](https://docs.github.com/en/actions/learn-github-actions/variables#using-the-vars-context-to-access-configuration-variable-values)
### Testing Instructions
Configure the remote cache, invoke GitHub Action, and check the logs.