function wfImagesInHTML(ast, file, setting) {
  visit(ast, 'html', function(node) {
    let matched = reImgSrc.exec(node.value);
    if (matched && matched[1]) {
      doesImageExist(file, matched[1], node);
    }
  });
}
Remark Lint Test - verifies html image files exist.

@param {Object} ast
@param {Object} file
@param {Object} setting