feat: Adds note about signing commits.

Yubikey.md

@@ -217,6 +217,11 @@ Remove the yubikey and try again, it shouldn't be possible without the yubikey b
 > being the important part
 > [stack-overflow-link](https://stackoverflow.com/questions/78554135/unverified-github-commits-using-gpg-keys-on-yubikey).
 
+## Signing Commits
+
+When signing commits it will ask for a PIN to unlock the card, here you need to use the GPG User PIN
+to unlock and sign the commit, not the pin for the private key.
+
 ## SSH setup
 
 [Setup Instructions](https://github.com/drduh/YubiKey-Guide?tab=readme-ov-file#ssh)