 update README with current documentation URL
 update README with current documentation URL

follow-up to 85cb90fbb21386583c5bc842bcee97c24e01a606
also extends the "using packages"
oscarfv/MINGW-packages,oscarfv/MINGW-packages,stahta01/MINGW-packages,JPeterMugaas/MINGW-packages,oroppas/MINGW-packages,Alexpux/MINGW-packages,JPeterMugaas/MINGW-packages,lhmouse/MINGW-packages,fabiangreffrath/MINGW-packages,stahta01/MINGW-packages,lhmouse/MINGW-packages,fabiangreffrath/MINGW-packages,JPeterMugaas/MINGW-packages,oscarfv/MINGW-packages,fabiangreffrath/MINGW-packages,oroppas/MINGW-packages,oscarfv/MINGW-packages,oscarfv/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,lhmouse/MINGW-packages,oroppas/MINGW-packages,fabiangreffrath/MINGW-packages,oroppas/MINGW-packages,oroppas/MINGW-packages,lhmouse/MINGW-packages,JPeterMugaas/MINGW-packages,Alexpux/MINGW-packages,Alexpux/MINGW-packages,Alexpux/MINGW-packages,JPeterMugaas/MINGW-packages,lhmouse/MINGW-packages,InitialForce/MINGW-packages,InitialForce/MINGW-packages,stahta01/MINGW-packages,stahta01/MINGW-packages,stahta01/MINGW-packages,oscarfv/MINGW-packages,Alexpux/MINGW-packages,InitialForce/MINGW-packages,JPeterMugaas/MINGW-packages,oroppas/MINGW-packages,Alexpux/MINGW-packages,fabiangreffrath/MINGW-packages,fabiangreffrath/MINGW-packages