Update README.md

Author: MichelLeBon

spring-data-mongodb/README.md

@@ -7,3 +7,4 @@
 - [A Guide to Queries in Spring Data MongoDB](http://www.baeldung.com/queries-in-spring-data-mongodb)
 - [Spring Data MongoDB – Indexes, Annotations and Converters](http://www.baeldung.com/spring-data-mongodb-index-annotations-converter)
 - [Custom Cascading in Spring Data MongoDB](http://www.baeldung.com/cascading-with-dbref-and-lifecycle-events-in-spring-data-mongodb)
+- [GridFS in Spring Data MongoDB](http://www.baeldung.com/spring-data-mongodb-gridfs)