Add mysql store to the readme (#279)

Add MySQL store to README

Signed-off-by: ./daniele <47982731+danielepintore@users.noreply.github.com>

README.md

@@ -77,6 +77,7 @@ Other implementations of the `sessions.Store` interface:
 - [github.com/dsoprea/go-appengine-sessioncascade](https://github.com/dsoprea/go-appengine-sessioncascade) - Memcache/Datastore/Context in AppEngine
 - [github.com/kidstuff/mongostore](https://github.com/kidstuff/mongostore) - MongoDB
 - [github.com/srinathgs/mysqlstore](https://github.com/srinathgs/mysqlstore) - MySQL
+- [github.com/danielepintore/gorilla-sessions-mysql](https://github.com/danielepintore/gorilla-sessions-mysql) - MySQL
 - [github.com/EnumApps/clustersqlstore](https://github.com/EnumApps/clustersqlstore) - MySQL Cluster
 - [github.com/antonlindstrom/pgstore](https://github.com/antonlindstrom/pgstore) - PostgreSQL
 - [github.com/boj/redistore](https://github.com/boj/redistore) - Redis