update README\

README.md

@@ -2,6 +2,12 @@
 
 Smimesign is an S/MIME signing utility that is compatible with Git. This allows developers to sign their Git commits and tags using X.509 certificates issued by pubic certificate authorities or their organization's internal certificate authority. Smimesign uses keys and certificates already stored in the *macOS Keychain* or the *Windows Certificate Store*.
 
+This project is pre-1.0, meaning that APIs and functionality may change without warning.
+
+## Contributing
+
+Different organizations do PKI differently and we weren't able to test everyone's setup. Contributions making this tool work better for your organization are welcome. See the [contributing docs](CONTRIBUTING.md) for more information on how to get involved.
+
 ## Git Signing, GnuPG, PKI, and S/MIME
 
 Git allows developers to sign their work using GnuPG. This is a form of public key cryptography whereby the notion of trust is distributed. The party verifying a signature may directly know of the signer's identity and public key, or the signer's identity may be vouched for by a third party known to the verifier. Through layers of "vouching", a web-of-trust is established.

command_sign.go

@@ -19,7 +19,7 @@ func commandSign() error {
 		return errors.Wrap(err, "failed to get identity matching specified user-id")
 	}
 	if userIdent == nil {
-		return fmt.Errorf("could not find identity matching specified user-id: %s\n", *localUserOpt)
+		return fmt.Errorf("could not find identity matching specified user-id: %s", *localUserOpt)
 	}
 
 	// Git is looking for "\n[GNUPG:] SIG_CREATED ", meaning we need to print a