Fix footer to say "Target Platforms" instead of falsely claiming "Tested On"

Co-authored-by: abossard <86611+abossard@users.noreply.github.com>

Author: Copilot

docs/INSTALL_UBUNTU.md

@@ -470,4 +470,4 @@ For more troubleshooting help, see [TROUBLESHOOTING.md](TROUBLESHOOTING.md).
 ---
 
 **Last Updated:** November 2024  
-**Tested On:** Ubuntu 22.04 LTS (Jammy Jellyfish), Ubuntu 24.04 LTS (Noble Numbat)
+**Target Platforms:** Ubuntu 22.04 LTS (Jammy Jellyfish), Ubuntu 24.04 LTS (Noble Numbat)