Add a link to javadoc

Author: lenkis

README.md

@@ -87,9 +87,11 @@ all the results, you could override this:
 protected void complete(long code, FutureImpl<List> q);
 ```
 
+For more implementation details, see [API documentation](http://tarantool.github.io/tarantool-java/apidocs/index.html).
+
 ## Where to get help
 
 Got problems or questions? Post them on
 [Stack Overflow](http://stackoverflow.com/questions/ask/advice) with the
 `tarantool` and `java` tags, or use these tags to search the existing knowledge
-base for possible answers and solutions.
+base for possible answers and solutions.