Adds a designated revoker to the key.
This method adds a designated revoker to the selected Key. The UserId parameter specifies the revoker to add. The revoker's key must be present in the current keyring. Use this with caution: once added, a revoker cannot be removed. The key's passphrase is required for this operation and may be specified via Passphrase or through the KeyPassphrase event.
The UserId format is:
FirstName LastName (Comment) <Email>Not all values are required when selecting or generating a key, but at least FirstName or Email are required.