update README.md

Author: Karlatemp

README.md

@@ -152,6 +152,7 @@ publishing {
    
       // Don't drop line breaks. An empty line is required for gradle to read the key
       "key": "-----BEGIN PGP PRIVATE KEY BLOCK-----\n\n.....\n-----END PGP PRIVATE KEY BLOCK-----",
+      // Optional. When the key has no password, remove this field
       "keyPassword": "The Password Of Your Key",
       // Optional. This field is optional. Used when you want to use a sub key to sign publications 
       "keyId": "Sub Key Id"