Update README to note newer maven version required
Update README to note newer maven version required

Incrementals support requires maven 3.5.4.

MarkEWaite/git-plugin,v1v/git-plugin,martinda/git-plugin,jenkinsci/git-plugin,jenkinsci/git-plugin,v1v/git-plugin,jenkinsci/git-plugin,martinda/git-plugin,MarkEWaite/git-plugin,MarkEWaite/git-plugin,v1v/git-plugin,martinda/git-plugin,jenkinsci/git-plugin,MarkEWaite/git-plugin