Update README.md

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Author: shawnxie94

README.md

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 # JavaCallGraph
+[![Java support](https://img.shields.io/badge/Java-8+-green?logo=java&logoColor=white)](https://openjdk.java.net/)
+[![License](https://img.shields.io/badge/license-MIT-blue?logo=opensourceinitiative&logoColor=white)](https://opensource.org/licenses/MIT)
+
 > Java implementation of CallGraph.
 
 CG的Java实现方式。采用源码和字节码静态分析方式，提供静态调用关系图和分支变更影响分析能力。