Consider using CF_USERNAME/CF_PASSWORD environment variables instead of positional args for cf auth

[mheadd]

Description

Following up on PR #4 (Focus auth on non-interactive usage), the authentication instructions currently show:

cf auth <USERNAME> <PASSWORD>

For CI/CD and agent-driven workflows, it may be safer to recommend using the CF_USERNAME and CF_PASSWORD environment variables instead:

export CF_USERNAME=<USERNAME>
export CF_PASSWORD=<PASSWORD>
cf auth

Rationale

• Avoids credentials in shell history — positional args are recorded in .bash_history and may appear in process listings
• Aligns with 12-factor principles — configuration via environment variables
• Standard CF CLI pattern — the CLI natively supports these env vars

References

• https://cli.cloudfoundry.org/en-US/v8/auth.html
• PR Focus auth on non-interactive usage #4: Focus auth on non-interactive usage #4

cc @mogul

[mogul]

The export statements would also appear in shell history. Better to recommend putting the var definitions in a .env file and then running source .env to set those env-vars, since agents know how to edit files natively.