docs: Add missing --force flag documentation (#12440)
## Description
This PR updates the Turbo CLI documentation to include the missing
`--force` (`-f`) flag for the `turbo login` command.
## Problem
The `--force` flag is supported by the CLI but was not documented in the
`login.mdx` reference page. This could lead to confusion for users who
want to re-authenticate or overwrite existing credentials.
## Changes
- Added documentation for the `--force` (`-f`) flag in:
- `apps/docs/content/docs/reference/login.mdx`
- Included a brief description explaining its purpose
- Added usage context to improve clarity for users
## Result
The documentation now accurately reflects the available CLI options,
improving developer experience and consistency between the CLI and docs.
## Related Issue
Closes #10625
Co-authored-by: Goldyvaiiii <01234567vss@gmail.com>
