Share the CommonMark grammar, close the guard's hole, refuse the lists no marker spells

src/index.ts

@@ -1,4 +1,5 @@
 export type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from './adf-document.ts'
 export type { ConvertError, ConvertErrorCode, Result } from './result.ts'
+export type { JsonValue } from './json-value.ts'
 export { adfToMarkdown } from './adf-to-markdown.ts'
 export { isAdfDocument } from './adf-document.ts'