doc: json support with node@12.7 esm modules
in node 12.7 documentation you have in https://nodejs.org/docs/v12.7.0/api/esm.html#esm_code_import_code_statements "JSON and Native modules are not supported"
but then go on in https://nodejs.org/docs/v12.7.0/api/esm.html#esm_json_modules and describe JSON support (which works fine)