Add README section for troubleshooting common connection problems

[DhanushNehru]

• Document common connection issues like “connection not ready” or peers not discovering each other, and list simple fixes (check same network, refresh, restart signaling server, allow permissions).
• Include a short FAQ subsection in README (e.g., “Why can’t I see other devices?”, “File transfer stuck at 0%”).

[alimhuduev-tech]

1."Connection not ready" WebRTC signaling is still in progress. Wait a few seconds or refresh both pages.
2.Peers not discovering each other Devices are on different networks or isolated.Ensure both devices are on the same Wi-Fi/LAN and can "see" each other.
3.Stuck at "Connecting..." Firewall or NAT blocking the P2P traffic. Check if a VPN is active; try disabling it. Ensure the signaling server is running.
4.Permission Denied Browser blocked necessary APIs (like camera/folders if used).Click the lock icon in the address bar and reset permissions.