docs: add connect-memjs to the list of session stores

closes #455

README.md

@@ -576,6 +576,12 @@ and other multi-core embedded devices).
 [connect-memcached-url]: https://www.npmjs.com/package/connect-memcached
 [connect-memcached-image]: https://img.shields.io/github/stars/balor/connect-memcached.svg?label=%E2%98%85
 
+[![★][connect-memjs-image] connect-memjs][connect-memjs-url] A memcached-based session store using
+[memjs](https://www.npmjs.com/package/memjs) as the memcached client.
+
+[connect-memjs-url]: https://www.npmjs.com/package/connect-memjs
+[connect-memjs-image]: https://img.shields.io/github/stars/liamdon/connect-memjs.svg?label=%E2%98%85
+
 [![★][connect-session-knex-image] connect-session-knex][connect-session-knex-url] A session store using
 [Knex.js](http://knexjs.org/), which is a SQL query builder for PostgreSQL, MySQL, MariaDB, SQLite3, and Oracle.