Utilities: Update LogoutHook/Launchd.command for earlier macOS

 - Compatible with earlier macOS (Snow Leopard+ tested)
 - Automatically installs as launch daemon (Yosemite+) or logout hook

Changelog.md

 OpenCore Changelog
 ==================
+#### v0.8.6
+- Updated emulated NVRAM save script for compatibilty with earlier macOS (Snow Leopard+ tested)
+- Updated emulated NVRAM save script to automatically install as launch daemon (Yosemite+) or logout hook
+
 #### v0.8.5
 - Updated builtin firmware versions for SMBIOS and the rest
 - Moved CPU objects that exist only in Windows Server 2022 into `SSDT-HV-DEV-WS2022.dsl`