update readme for 4.x
update readme for 4.x

IBBoard/news,owncloud/news,Xefir/news,owncloud/news,IBBoard/news,Xefir/news,IBBoard/news,itstar4tech/news,Xefir/news,itstar4tech/news,itstar4tech/news,itstar4tech/news,Xefir/news,IBBoard/news,owncloud/news