Sleep wait enhancement

[thwkai]

I took the liberty to make a small update to the README and added a "new feature" that introduces a configurable wait period (sleep) before the container exits.

Details:

• README.md – Added a hint on how to determine the ID of an Organisationseinheit.
• README.md – Fixed a minor typo.
• config.json.sample – Added a sleep variable (default: 0).
• divera.py – Added a conditional block at the end of the script. If the 'sleep' config value is set and greater than 0, the script will pause for the specified number of minutes before exiting. Also added the required import time.

Rationale for the sleep feature:
In my setup, I manage Docker containers fully automatically (including automated GHCR builds) using Portainer stacks. In the current release version, this leads to an undesired loop: the container is restarted immediately after finishing. To prevent this, I introduced a configurable sleep timer at the end of the script. This ensures the container remains running for a defined period before exiting (and being automatically restarted). In my case, I chose a 15-minute delay, effectively throttling the re-run interval of the status sync.