After implementation of raising an error for identifiers with supplement but without publication year for base identifier we cannot parse identifiers like "ISO/IEC FDIS 23008-1/WD Amd 1" (https://www.iso.org/standard/82727.html).
So we need to raise an error only if document with supplement don't have stage or publication year.
Also add a note to the README and Rubydoc to the error class.
related #117
After implementation of raising an error for identifiers with supplement but without publication year for base identifier we cannot parse identifiers like "ISO/IEC FDIS 23008-1/WD Amd 1" (https://www.iso.org/standard/82727.html). So we need to raise an error only if document with supplement don't have stage or publication year.
Also add a note to the README and Rubydoc to the error class.