Add markdown format support (#25)

Co-authored-by: Dawid Dziurla <dawidd0811@gmail.com>

node_modules/require-main-filename/index.js

@@ -0,0 +1,18 @@
+module.exports = function (_require) {
+  _require = _require || require
+  var main = _require.main
+  if (main && isIISNode(main)) return handleIISNode(main)
+  else return main ? main.filename : process.cwd()
+}
+
+function isIISNode (main) {
+  return /\\iisnode\\/.test(main.filename)
+}
+
+function handleIISNode (main) {
+  if (!main.children.length) {
+    return main.filename
+  } else {
+    return main.children[0].filename
+  }
+}