I would recommend to use the site-maven-plugin following part to distribute generated sites to github:
<profile>
<id>github</id>
<build>
<plugins>
<plugin>
<groupId>com.github.github</groupId>
<artifactId>site-maven-plugin</artifactId>
<version>0.8</version>
<configuration>
<message>Creating site for ${project.version}</message>
<server>github</server>
</configuration>
<executions>
<execution>
<goals>
<goal>site</goal>
</goals>
<phase>post-site</phase>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>
To preview your site before publishing you can use the stage goal of maven-site-plugin like this:
mvn site:stage -DstagingDirectory=C:\fullsite