docs(upgrade) add 0.6.x upgrade path
docs(upgrade) add 0.6.x upgrade path

ajayk/kong,smanolache/kong,ccyphers/kong,salazar/kong,Kong/kong,xvaara/kong,Vermeille/kong,li-wl/kong,icyxp/kong,Mashape/kong,akh00/kong,Kong/kong,jebenexer/kong,Kong/kong,jerizm/kong,beauli/kong,shiprabehera/kong