update readme about jitpack dependecy instruction

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>
`