update readme about jitpack dependecy instruction

[marwin1991]

Hello, on readme there is a section how to add this lib to depnedencies and it is diffrent than on jitpack. In my opinion it should be:

<dependency> <groupId>com.github.Steppschuh</groupId> <artifactId>Java-Markdown-Generator</artifactId> <version>1.3.2</version> </dependency>