[feat] Add interfaces.md

Author: mikoto2464

docs/computer-programming-with-java-language/index-zh-CN.md

@@ -10,7 +10,9 @@ Java是一门语言，是一门纯粹的面向对象程序设计语言，而我
 
 ## 目录
 
+ - 1 **初识Java**
  - 1.0 [类和对象](classes-and-objects-zh-CN.md)
+ - 1.1 [接口](interfaces-zh-CN.md)
 
 ## 参考书目与资料
 

docs/computer-programming-with-java-language/index.md

@@ -10,7 +10,9 @@ Java is a language, a pure object-oriented programming language, and what we hav
 
 ## Table of contents
 
-- 1.0 [Classes and Objects](classes-and-objects.md)
+ - 1 Getting to know Java
+ - 1.0 [Classes and Objects](classes-and-objects.md)
+ - 1.1 [Interfaces](interfaces.md)
 
 ## Bibliography and Materials