add short readme

README.md

@@ -0,0 +1,13 @@
+# node-fetch-cookies
+node-fetch wrapper that adds support for cookie-jars
+
+## Example Usage
+```javascript
+import cookies from "node-fetch-cookies";
+// "rw" are the flags, meaning cookies will be read and written from/to the cookie jar. r = read, w = write
+// second argument is the filename, can also be undefined if you don't want to read/write the cookies from/to a file
+let cookieJar = new cookies.CookieJar("rw", "path/to/file.json");
+// first parameter is the url, second the options, just like node-fetch. third parameter is the cookie jar
+// returns a response object just like node-fetch
+cookies.fetch("https://example.page/example/path", null, cookieJar);
+```