Environment Variable Documentation Generator — illustrative example

INPUT
Document APP_PORT (listening port) and SMTP_PASSWORD (mail service credential). Defaults, requiredness and code locations have not been supplied.

RESULT
APP_PORT
Purpose: port on which the application listens.
Example: 3000 (illustrative, not a confirmed default).
Default / required / code location: confirm from the application.

SMTP_PASSWORD
Purpose: credential for the configured mail service.
Example value: <set-through-secret-configuration>.
Default / required / code location: confirm from the mail integration.
Keep the real credential out of shared examples and version control.

REVIEW
Document configuration names, purpose and defaults without exposing actual secrets. Identify whether a variable is required and where it is read.

This is a teaching example, not a live execution record.