Update settings.md for adguard-vpn-for-linux

[SelYui]

• Added new setting set-use-quic for enabling or disabling QUIC protocol
• Replaced "No-route mode" section with new settings:
  • set-tun-routing-mode: Set the VPN tunnel routing mode (auto, script, none)
  • create-routes-script: Create routes script with proper permissions
• Added new section "SOCKS settings" with commands:
  • set-socks-host: Set the SOCKS listen host
  • set-socks-username: Set the SOCKS username
  • set-socks-password: Set the SOCKS password
  • clear-socks-auth: Clear the SOCKS username and password