Plasma Release Schedule Updated

I’ve made some changes to the Plasma 5.8 release schedule.  We had a request from our friends at openSUSE to bring the release sooner by a couple of weeks so they could sneak it into their release and everyone could enjoy the LTS goodness.  As openSUSE are long term supporters and contributors to KDE as well as patrons of KDE the Plasma team chatted and decided to slide the dates around to help out.  Release is now on the first Tuesday in October.