Fixed label in license badge.
Documented Gradle plugin portal usage of auto-value plugin.
Fixed documentation error for auto-value plugin config.
Improved the auto-value-plugin.

The DSL configuration option 'delete' was removed. The plugin now features a clean tasks that is called on project clean. The default generated source folder has been changed to 'src/auto-value/java'. The source created is named 'autoValue'. Also added some minor tweaks.
Ready documentation was split up into plugin wise organisation.