Document or declare the htpasswd module requirement #8

I hit a module resolution failure when running this role in a clean ansible-core environment.

Observed failure:

• With ansible-core 2.15, the role fails while resolving the bare htpasswd module in tasks/main.yml.

Error excerpt:

ERROR! couldn't resolve module/action 'htpasswd'. This often indicates a misspelling, missing collection, or incorrect module path.

The error appears to be in 'tasks/main.yml' at the task named:

- name: Ensure htpasswd credentials are configured.

This may not show up when using the full ansible distribution or a test environment that already includes community collections. For ansible-core-only installs, the role likely needs an explicit documented collection requirement or a fully qualified module reference for the htpasswd task.