Add reference to the visual repository overview (#807)

Adding a link to the high-level diagrams including module, library dependency and others (https://sourcespy.com/github/alibabajetcache/). Built directly from source and updated on schedule. Intended to simplify developer's introduction to the project.

In the spirit of transparency - I am the author of the diagrams. Hope contributors find it useful.

docs/EN/Readme.md

@@ -38,7 +38,8 @@ see *samples* directory of the repository.
 * [In-memory ```Cache``` implements: LinkedHashMapCache and CaffeineCache](Embedded.md)
 * [Statistics](Stat.md)
 * [Builder API](Builder.md): If you do not use Spring Framework or want to construct ```Cache``` instance by hand coding
-* [Compatibility notes](Compatibility.md) 
+* [Compatibility notes](Compatibility.md)
+* [Repository Map](https://sourcespy.com/github/alibabajetcache/): a visual introduciton to the repository
 
 ## which artifact should I use?
 * jetcache-anno-api: define annotation and constants, no transitive dependencies. If you want to add JetCache annotation to your API artifact without introduce a lot of dependencies, you use jetcache-anno-api. 

readme.MD

@@ -2,6 +2,7 @@
 [![Coverage Status](https://coveralls.io/repos/github/alibaba/jetcache/badge.svg?branch=master)](https://coveralls.io/github/alibaba/jetcache?branch=master)
 [![GitHub release](https://img.shields.io/github/release/alibaba/jetcache.svg)](https://github.com/alibaba/jetcache/releases)
 [![License](https://img.shields.io/badge/license-Apache%202-4EB1BA.svg)](https://www.apache.org/licenses/LICENSE-2.0.html)
+[![Project Map](https://sourcespy.com/shield.svg)](https://sourcespy.com/github/alibabajetcache/)
 
 # Introduction
 JetCache is a Java cache abstraction which provides uniform usage for different caching solutions.