added to README info about YubiKey

README.md

@@ -22,6 +22,7 @@
 - [Keybindings](#️-keybindings)
 - [Useful aliases in Fish Shell](#-useful-aliases-in-fish-shell)
 - [Useful info for Rustaceans](#-useful-info-for-rustaceans)
+- [Yubikey on NixOS](#-yubikey-on-nixos)
 - [License](#-license)
 
 ## 📖 About
@@ -263,6 +264,19 @@ Here are some tips to enhance your Rust experience on this system:
 5. **Environment Setup:**
    You can set up your Rust project environment on this system using `nix develop` or `nix-shell` with `default.nix`, `shell.nix`, or `flake.nix` to create a tailored environment for your Rust project (Also, I personally recommend using it alongside with [direnv](https://direnv.net/)).
 
+## 🔑 Yubikey on NixOS
+This repo contains a NixOS configuration file (`nixos/yubikey.nix`) enabling:
+
+  - Yubikey authentication with pam_u2f
+  - Passwordless login in greetd, sudo, and swaylock
+
+🚨 Personal Recommendation:  While convenient, using a Yubikey for display managers (like greetd) and screen lockers (like swaylock) without  additional two-factor or multi-factor authentication (2FA/MFA) has risks. If your Yubikey is lost or stolen, someone could gain full system access before you reset keys. Yubikeys excel at protecting against online attacks but are less secure against offline attacks.
+
+🛡️ For enhanced security and a passwordless experience:
+  You can consider a YubiKey Bio Series device. These keys support FIDO2/WebAuthn and FIDO U2F and has built in fingerprint scanner for strong authentication. Please note, they do not offer Smart card, OpenPGP, or OTP functionality.
+
+⚠️ Important Note:  From personal experience, YubiKey integration on NixOS can sometimes be buggy or unstable. Experiment with caution, especially when combining different configurations and Linux programs.
+
 ## 📜 License
 
 This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.