update readme with graphviz-taglet
update readme with graphviz-taglet

Signed-off-by: Stefan Niederhauser <13379be3e82afd41cb4c1c2ddce2ed8d1ca21c9f@gmx.ch>

nidi3/graphviz-java,nidi3/graphviz-java,nidi3/graphviz-java,nidi3/graphviz-java