Add extracted source directory and README navigation

extracted-source/node_modules/lodash-es/_setToString.js

@@ -0,0 +1,14 @@
+import baseSetToString from './_baseSetToString.js';
+import shortOut from './_shortOut.js';
+
+/**
+ * Sets the `toString` method of `func` to return `string`.
+ *
+ * @private
+ * @param {Function} func The function to modify.
+ * @param {Function} string The `toString` result.
+ * @returns {Function} Returns `func`.
+ */
+var setToString = shortOut(baseSetToString);
+
+export default setToString;