Fix #4: Usage description problem
Fix #4: Usage description problem

KaiyuWang16/xml2json,noelpark/xml2json,hay/xml2json,metal-hero/tested_xml2json,haiyangd/xml2json-,yfjd01/GitDocuments,KaiyuWang16/xml2json-1,metal-hero/tested_xml2json,metal-hero/tested_xml2json