Add extracted source directory and README navigation

extracted-source/node_modules/parse5/lib/utils/merge-options.js

@@ -0,0 +1,13 @@
+'use strict';
+
+module.exports = function mergeOptions(defaults, options) {
+    options = options || Object.create(null);
+
+    return [defaults, options].reduce((merged, optObj) => {
+        Object.keys(optObj).forEach(key => {
+            merged[key] = optObj[key];
+        });
+
+        return merged;
+    }, Object.create(null));
+};