add snapshot repository url

README.md

@@ -26,7 +26,16 @@ You can find some slides about Easy Rules on [speaker deck](https://speakerdeck.
 ## Current version
 
 * The current stable version is 1.3.0: [![Build Status](https://buildhive.cloudbees.com/job/benas/job/easy-rules/badge/icon)](https://buildhive.cloudbees.com/job/benas/job/easy-rules/)
-* The current development version is 1.4.0-SNAPSHOT
+* The current development version is 1.4.0-SNAPSHOT. In order to use snapshot versions, you need to add the following maven repository in your `pom.xml`:
+
+```xml
+<repositories>
+    <repository>
+        <id>ossrh</id>
+        <url>https://oss.sonatype.org/content/repositories/snapshots</url>
+    </repository>
+</repositories>
+```
 
 ## Agile Board
 [Backlog items @ waffle.io](https://waffle.io/benas/easy-rules)