add service TruenasScale, view status and version

[thibaut1304]

Description

Added a new service integration to monitor a Truenas Scale status.

📌 Issue :
There was no way to check if a TrueNas Scale was online or to display its version from the dashboard.

✅ Solution :

• Query the Truenas /api/v2.0/system/version endpoint to get the version string.
• Checks connectivity to determine whether the service is online or offline.
• Displays the version and status in the card.
• Updated the customservices.md documentation with usage instructions.

🔥 Motivation :
Allow users to monitor the availability and version of their TrueNas Scale directly in Homer.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I've read & comply with the contributing guidelines
• I have tested my code for new features & regressions on both mobile & desktop devices, using the latest version of major browsers.
• I have made corresponding changes to the documentation (README.md).
• I've checked my modifications for any breaking changes, especially in the config.yml file