Add maven coordinates (#80)

Add macen coordinates

Author: koppor

README.md

@@ -261,4 +261,8 @@ MyObject actual = JsonValue.of( """
     {"tags": ["intro", "hello"]}""" ).as( MyObject.clas );
 
 JsonDiff diff1 = expected.diff( actual ); // same
-```
+```
+
+## Maven cooordinates
+
+The maven coordinates are [`org.hisp.dhis:json-tree`](https://search.maven.org/artifact/org.hisp.dhis/json-tree).