Add stringification as fenced code blocks when missing value and language
Add stringification as fenced code blocks when missing value and language

eush77/remark,chcokr/mdast,chcokr/mdast,eush77/remark,ulrikaugustsson/mdast,wooorm/remark,ulrikaugustsson/mdast,yukkurisinai/mdast,tanzania82/remarks,yukkurisinai/mdast