Update README to include more detail
Update README to include more detail

The user is now pointed to download the latest release rather the the master repo contents
Caoimhinmg/PmagPy,lfairchild/PmagPy,Caoimhinmg/PmagPy,Caoimhinmg/PmagPy,lfairchild/PmagPy,lfairchild/PmagPy