add readme for exceptions

README.md

@@ -31,3 +31,12 @@ app.use(auth((user_name) => {
 
 when a client logs in, it will set a header called 'session' that the client can use to authorize the following requests.
 it also sets a cookie to make requesting from the client more simple. (cookie parser is needed to make authentication with cookies possible)
+
+## Excluding routes
+
+exceptions to the auth module can be added by adding an array of regular expressions
+a specific method can also be filtered for by giving an object instead of a plain regular expression.
+
+```js
+auth(..., [/no-auth/, {regex: '/no-auth-post/', method: 'POST'}]);
+```